Tutorial Ansys TurboGrid

ANSYS TurboGrid Tutorials

Release 14.5ANSYS, Inc.

October 2012Southpointe

275 Technology Drive

Canonsburg, PA 15317 ANSYS, Inc. is

certified to ISO

9001:[email protected]

http://www.ansys.com

(T) 724-746-3304

(F) 724-514-9494

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THIS ANSYS SOFTWARE PRODUCT AND PROGRAM DOCUMENTATION INCLUDE TRADE SECRETS AND ARE CONFID-

ENTIAL AND PROPRIETARY PRODUCTS OF ANSYS, INC., ITS SUBSIDIARIES, OR LICENSORS. The software products

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Published in the U.S.A.

Table of Contents

1. Introduction to the ANSYS TurboGrid Tutorials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.1. Preparing a Working Directory .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.2. Setting the Working Directory and Starting ANSYS TurboGrid .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.3. Changing the Display Colors ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.4. Editor Buttons .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.5. Using Help .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2. Rotor 37 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.1. Overview of the Mesh Creation Process .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2.2. Before You Begin .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.3. Starting ANSYS TurboGrid .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.4. Defining the Geometry .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.5. Defining the Topology .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

2.6. Reviewing the Mesh Data Settings .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

2.7. Reviewing the Mesh Quality on the Hub and Shroud Tip Layers ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

2.8. Generating the Mesh .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2.9. Looking at Mesh Data Values .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2.10. Analyzing the Mesh Quality ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2.11. Visualizing the Hub-to-Shroud Element Distribution .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2.12. Observing the Shroud Tip Mesh .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

2.13. Examining the Mesh Qualitatively .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

2.14. Creating a Legend .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

2.15. Saving the Mesh .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

2.16. Saving the State (Optional) ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

3. Steam Stator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3.1. Before You Begin .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3.2. Starting ANSYS TurboGrid .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3.3. Defining the Geometry .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3.3.1. Loading the Curves .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

3.3.2. Setting the Curve Type .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

3.4. Defining the Topology .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

3.5. Reviewing the Mesh Data Settings .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

3.6. Reviewing the Mesh Quality on the Hub and Shroud Layers ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

3.7. Generating the Mesh .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

3.8. Analyzing the Mesh .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

3.8.1. Examining the Mesh Qualitatively .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

3.8.1.1. Editing a Turbo Surface .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

3.8.1.2. Creating a Legend .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

3.9. Saving the Mesh .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22


4. Radial Compressor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

4.1. Before You Begin .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24



4.3.1. Defining the Machine Data .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

4.3.2. Defining the Hub .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

4.3.3. Defining the Shroud .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

4.3.4. Defining the Blade .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

4.3.5. Defining the Splitter Blade .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28



iiiRelease 14.5 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information

of ANSYS, Inc. and its subsidiaries and affiliates.



4.8. Saving the Mesh .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

4.9. Saving the State (Optional) ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

5. Axial Fan Using ATM Optimized Topology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

5.1. Before You Begin .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34




5.5. Increasing the Mesh Density .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37


5.7. Using the Locking Feature .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

5.8. The Y+ Functionality ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

5.9. Using Local Mesh Refinement .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

5.10. Analyzing the Mesh .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

5.11. Adding Inlet and Outlet Domains .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

5.12. Analyzing the New Mesh .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

5.13. Saving the Mesh .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42


6. Axial Fan Using Traditional Topology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

6.1. Before You Begin .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44





6.6. Reviewing the Mesh Quality on the Hub and Shroud Tip Layers ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

6.6.1. Modifying the Shroud Tip Layer .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

6.7. Adding Intermediate Layers ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49



6.10. Adding Inlet and Outlet Domains .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

6.11. Regenerating the Mesh .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

6.12. Analyzing the New Mesh .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

6.13. Saving the Mesh .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52


7. Splitter Blades . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

7.1. Before You Begin .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54




7.5. Reviewing the Topology Settings .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55



7.7.1. Modifying the Hub Layer .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56



7.10. Saving the Mesh .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58


8. Tandem Vane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

8.1. Before You Begin .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60



Release 14.5 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential informationof ANSYS, Inc. and its subsidiaries and affiliates.iv

Tutorials


8.5. Reviewing the Topology Settings .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62



8.7.1. Modifying the Hub Layer .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

8.7.2. Modifying the Shroud Tip Layer .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

8.8. Increasing the Mesh Density .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

8.9. Further Modifying the Hub Layer .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

8.10. Generating the Mesh .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

8.11. Saving the Mesh .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69


9. Batch Mode Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

9.1. Before You Begin .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

9.2. Part 1: Parametric Study .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

9.2.1. Starting ANSYS TurboGrid .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

9.2.2. Defining the Geometry .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

9.2.3. Creating the Topology and Modifying the Mesh .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

9.2.4. Creating the Session File ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

9.2.5. Running the Session File ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

9.3. Part 2: Grid Refinement .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

9.3.1. Starting ANSYS TurboGrid .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

9.3.2. Defining the Geometry and Topology .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

9.3.3. Creating the Session File ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

9.3.4. Running the Session File ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

10. Deformed Turbine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

10.1. Before You Begin .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

10.2. Starting ANSYS TurboGrid .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

10.3. Mesh for the Deformed Blade Group .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

10.3.1. Defining the Geometry for the Deformed Blade Group .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

10.3.1.1. Loading an Undeformed Blade .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

10.3.1.2. Moving the Periodic Surfaces .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

10.3.1.3. Inserting Two More Blades .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

10.3.1.4. Adding a Shroud Tip .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

10.3.1.5. Adjusting the Inlet and Outlet Points ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

10.3.1.6. Saving the Periodic/Interface Surfaces .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

10.3.1.7. Saving the Inlet and Outlet Locations .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

10.3.2. Defining the Topology for the Deformed Blade Group .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

10.3.3. Reviewing the Mesh Data Settings for the Deformed Blade Group .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

10.3.4. Reviewing the Mesh Quality on the Hub and Shroud Tip Layers of the Deformed Blade

Group .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

10.3.4.1. Modifying the Hub Layer .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

10.3.4.2. Modifying the Shroud Tip Layer .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

10.3.5. Increasing the Mesh Density for the Deformed Blade Group .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

10.3.6. Revisiting the Mesh Quality on the Hub and Shroud Tip Layers of the Deformed Blade

Group .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

10.3.7. Generating the Mesh for the Deformed Blade Group .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

10.3.8. Analyzing the Mesh for the Deformed Blade Group .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

10.3.9. Saving the Mesh for the Deformed Blade Group .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

10.3.10. Saving the State for the Deformed Blade Group (Optional) ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

10.4. Mesh for an Undeformed Blade .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

10.4.1. Starting a New Case .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

10.4.2. Defining the Geometry for the Undeformed Blade .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

vRelease 14.5 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information


Tutorials

10.4.2.1. Adding a Shroud Tip .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98

10.4.3. Defining the Topology for the Undeformed Blade .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98

10.4.4. Reviewing the Mesh Data Settings for the Undeformed Blade .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

10.4.5. Reviewing the Mesh Quality on the Hub and Shroud Tip Layers of the Undeformed Blade .... . . 99

10.4.5.1. Modifying the Hub Layer .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

10.4.6. Increasing the Mesh Density for the Undeformed Blade .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

10.4.7. Revisiting the Mesh Quality on the Hub and Shroud Tip Layers of the Undeformed Blade .... . 102

10.4.8. Generating the Mesh for the Undeformed Blade .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

10.4.9. Analyzing the Mesh for the Undeformed Blade .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

10.4.10. Saving the Mesh for the Undeformed Blade .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

10.4.11. Saving the State for the Undeformed Blade (Optional) ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

10.5. Summary .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

10.6. Further Exercise .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

11. Francis Turbine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

11.1. Before You Begin .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

11.2. Starting ANSYS TurboGrid .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

11.3. Defining the Geometry .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

11.3.1. Adjusting the Outlet Points ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

11.4. Defining the Topology .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

11.5. Reviewing the Mesh Quality on the Hub and Shroud Layers ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

11.5.1. Modifying the Hub Layer .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

11.5.2. Modifying the Shroud Layer .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

11.6. Specifying Mesh Data Settings .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

11.7. Generating the Mesh .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116

11.8. Analyzing the Mesh .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116

11.9. Saving the Mesh .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116

11.10. Saving the State (Optional) ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116

Index .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117

Release 14.5 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential informationof ANSYS, Inc. and its subsidiaries and affiliates.vi

Tutorials

Chapter 1: Introduction to the ANSYS TurboGrid Tutorials

The ANSYS TurboGrid tutorials are designed to introduce general mesh-generation techniques used in

ANSYS TurboGrid.

Note

These tutorials assume that you are using ANSYS TurboGrid in stand-alone mode. If you

would like to attempt running one of these tutorials in ANSYS Workbench, you should first

be familiar with ANSYS Workbench and review the documentation in ANSYS TurboGrid in

ANSYS Workbench in the TurboGrid Introduction.

You should review the following topics before attempting to start a tutorial for the first time:

1.1. Preparing a Working Directory

1.2. Setting the Working Directory and Starting ANSYS TurboGrid

1.3. Changing the Display Colors

1.4. Editor Buttons

1.5. Using Help

1.1. Preparing a Working Directory

ANSYS TurboGrid uses a working directory as the default location for loading and saving files for a

particular session or project. Before you run a tutorial, you must create a working directory and copy

in the files that are listed near the top of the tutorial. This practice will prevent you from making acci-

dental changes to any of the files that came with your installation. The files are available from your

ANSYS TurboGrid installation and from the ANSYS Customer Portal.

The tutorial input files are available in your ANSYS TurboGrid installation in <CFXROOT>/examples ,

where <CFXROOT> is the installation directory for ANSYS TurboGrid.

To access tutorials and their input files on the ANSYS Customer Portal, go to http://support.ansys.com/

training.

1.2. Setting the Working Directory and Starting ANSYS TurboGrid

Before you start ANSYS TurboGrid, set the working directory.

1. Start the ANSYS TurboGrid Launcher.

For details, see Starting the ANSYS TurboGrid Launcher in the TurboGrid Introduction.

2. Select a working directory.

3. Click the TurboGrid 14.5 button.

1Release 14.5 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information


http://support.ansys.com/training

http://support.ansys.com/training

1.3. Changing the Display Colors

If viewing objects in ANSYS TurboGrid becomes difficult due to contrast with the background, the colors

can be altered for improved viewing. You can access the color options by going through the following

steps:

1. Select Edit > Options.

The Options dialog box appears.

2. Adjust the color settings under TurboGrid > Viewer .

3. Click OK.

1.4. Editor Buttons

The ANSYS TurboGrid interface uses editors to enter the data required to create a mesh. The editors

have standard buttons, which are described next:

• Apply applies the information contained within all the tabs of an editor.

• OK is the same as Apply, except that the editor automatically closes.

• Cancel and Close both close the editor without applying or saving any changes.

• Reset returns the settings for the object to those stored in the database for all the tabs. The settings are

stored in the database each time the Apply button is clicked.

• Defaults restores the system default settings for all the tabs of the edited object.

1.5. Using Help

To invoke the help browser, select Help > Contents.

You may also try using context-sensitive help. Context-sensitive help is provided for many of the object

editors and other parts of the interface. To invoke the context-sensitive help for a particular editor or

other feature, ensure that the feature is active, place the mouse pointer over it, then press F1. Not every

area of the interface supports context-sensitive help. If context-sensitive help is not available for the

feature of interest, select Help > Contents and try using the search or index features in the help browser.

Release 14.5 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential informationof ANSYS, Inc. and its subsidiaries and affiliates.2

Introduction to the ANSYS TurboGrid Tutorials

Chapter 2: Rotor 37

This tutorial includes:

2.1. Overview of the Mesh Creation Process

2.2. Before You Begin

2.3. Starting ANSYS TurboGrid

2.4. Defining the Geometry

2.5. Defining the Topology

2.6. Reviewing the Mesh Data Settings

2.7. Reviewing the Mesh Quality on the Hub and Shroud Tip Layers

2.8. Generating the Mesh

2.9. Looking at Mesh Data Values

2.10. Analyzing the Mesh Quality

2.11.Visualizing the Hub-to-Shroud Element Distribution

2.12. Observing the Shroud Tip Mesh

2.13. Examining the Mesh Qualitatively

2.14. Creating a Legend

2.15. Saving the Mesh

2.16. Saving the State (Optional)

This tutorial demonstrates the basic workflow for generating a CFD mesh using ANSYS TurboGrid. As

you work through this tutorial, you will create a mesh for a blade passage of an axial compressor blade

row. A typical blade passage is shown by the black outline in the figure below.



The blade row contains 36 blades that revolve about the negative Z-axis. A clearance gap exists between

the blades and the shroud, with a width of 2.5% of the total span. Within the blade passage, the max-

imum diameter of the shroud is approximately 51 cm.

You will save the mesh in a format that can be used by ANSYS CFX in a CFD simulation.

2.1. Overview of the Mesh Creation Process

Before ANSYS TurboGrid can create a mesh, you must provide it with several pieces of information.

Such information includes the location of the geometry files (hub, shroud, and blades), the mesh topology

type, and the distribution of mesh nodes. All of the data that you provide is stored in a set of data objects

known as CCL objects. After you have specified the CCL objects appropriately, you can issue a command

for ANSYS TurboGrid to generate a mesh.

The ANSYS TurboGrid user interface organizes the CCL objects in a tree view known as the object selector.

You can use the object selector to select and edit the CCL objects; the objects are listed from top to

bottom in the standard order for creating a mesh. The user interface also has a toolbar for selecting

and editing the CCL objects; the icons are arranged from left to right in the standard order for creating

a mesh.

Regardless of whether you use the object selector or the toolbar, you should generally follow this se-

quence when creating a mesh:


Rotor 37

1. Define the geometry by loading files and changing settings as required.

2. Define the topology by choosing a topology type and optionally changing other topology settings.

3. Optionally modify the Mesh Data settings that govern the number and the distribution of nodes in

various parts of the mesh.

If you plan to make a fine (high-resolution) mesh, you can optionally set the mesh density at a

later time in order to minimize processing time while establishing the topology. Keep in mind that

changing the mesh density can affect the mesh quality.

4. Improve the topology on the hub and shroud layers as required.

5. Optionally add intermediate 2D layers that guide the 3D topology and mesh. If you do not add layers

at this point, they will be added as required when you generate the mesh. Adding them early gives

you a chance to check and adjust the 2D mesh quality on the intermediate layers before generating

the full 3D mesh.

6. Issue the command to generate a mesh.

7. Check the mesh quality. As required, adjust the topology type and distribution, and Mesh Data settings.

If you make changes, go back to the previous step.

8. Save the mesh to a file.


Before you begin this tutorial, review the topics in Introduction to the ANSYS TurboGrid Tutorials (p. 1).


1. Prepare the working directory using the files in the examples/rotor37 directory.

For details, see Preparing a Working Directory (p. 1).

2. Set the working directory and start ANSYS TurboGrid.

For details, see Setting the Working Directory and Starting ANSYS TurboGrid (p. 1).


The provided geometry files, which consist of a BladeGen.inf file plus three curve files, were created

using BladeGen. To load the information contained in those files, you will load the BladeGen.inffile. ANSYS TurboGrid uses this file to set the axis of rotation, the number of blades, and a length unit

that characterizes the scale of the machine. It also uses this file to identify the curve files which it then

loads to define the curvature of the hub, shroud, and a single blade. The geometric data from the input

files is processed to generate a geometric representation, an outline of which appears in the viewer.

After the geometry has been generated, you are invited to browse through the objects created under

the Geometry object in the object selector.

Initially, the blades extend from the hub to the shroud. After inspecting the geometry, you will create

the required gap between the blade and the shroud.



Defining the Geometry

Load the BladeGen.inf file:

1. Click File > Load BladeGen.

2. Open BladeGen.inf from the working directory.

The progress bar at the bottom right of the screen shows the geometry generation progress. After

the geometry has been generated, you can see the hub, shroud, and blade for one passage. Along

the blade, you can see the leading and trailing edge curves (green and red lines, respectively). An

outline drawing (the Outline object) traces the 3D space that is available for meshing; the latter

consists of an inlet domain, passage, and outlet domain. In this tutorial, you will generate a mesh

for the passage only.

Note

It is possible to adjust the upstream and downstream extents of the hub and shroud

surfaces (by changing the Inlet and Outlet geometry objects). It is also possible to

create an extended mesh that includes the inlet and outlet domains (by editing the

Mesh Data settings).

Examine the geometry in the 3D Viewer:

1. Toggle the visibility check box next to each object in the object selector and observe the change in

the viewer.

Note the correlation between the geometry objects listed in the object selector and the locations

in the geometry.

2. In order to avoid cluttering the view, ensure that the visibility is turned on only for these objects: Hub,

Shroud , Blade 1 , Outline .

Examine and set the machine type:

1. Open Geometry > Machine Data from the object selector by double-clicking Machine Data in

the object selector, or by right-clicking Machine Data and selecting Edit from the shortcut menu

that appears.

Here you can see basic information about the geometry. Note that the units specified for BaseUnits represent the scale of the geometry being meshed; these units are not used for importing

geometric data nor do they govern the units written to a mesh file; they are used for the internal

representation of the geometry to minimize computer round-off errors.

2. Set Machine Type to Axial Compressor.

Setting the machine type helps TurboGrid choose appropriate topology templates later in the mesh

creation process.

3. Click Apply.

Examine the hub:

1. Open Geometry > Hub.


Rotor 37

Here you can see information about which file was used for hub data and how the file was inter-

preted. Similar information can be seen by opening the Shroud and Blade 1 objects. Note that,

for the Hub and Shroud objects, the Curve Type parameter is set to Piece-wise linear ;

this is a result of loading a BladeGen.inf file.

2. Click Display all blade instances to obtain a view of the entire geometry.

3. Click Display single blade instance to show a single blade instance once again.

To complete the geometry, create a small gap between the blade and the shroud. The blade should

be shortened to 97.5% of its original span because the gap width, as specified in the problem description,

is 2.5% of the total span.

1. Open Geometry > Blade Set > Shroud Tip .

2. Set Tip Option to Constant Span .

3. Set Span to 0.975 .

4. Click Apply.

The names of the objects in the Geometry branch of the object selector are shown in black non-italic

text, indicating that the Geometry objects are all defined. This completes the geometry definition.


Now that the geometry is defined, the next step is to create the topology that guides the mesh.

This tutorial uses the ATM Optimized topology feature. ATM topology is a method for creating a mesh.

It allows you control over the global mesh size as well as the mesh size at the boundary layer. This

method of meshing is generally easier to use than the traditional topology methods (which are described

in Traditional Topologies). It also tends to result in better mesh quality.

1. Open Topology Set .

2. Set Topology Definition > Placement to ATM Optimized .

This provides access to the ATM topology method. The other option, Traditional withControl Points , provides access to the legacy topology methods.

3. Click Apply.

4. Right-click Topology Set and turn off Suspend Object Updates.

The Topology Set object name in the object selector changes to black non-italic text, indicating

that this object is now fully specified and has been generated.

After a short time, the topology appears on the hub and shroud as a structure of thick lines. Thinner

lines show a preview of the mesh elements.

Object updates are suspended by default. To save computational time, you should generally keep

object updates suspended until you have finished defining the geometry.



Defining the Topology

Estimates of the numbers of total nodes and total elements are displayed at the bottom left of the

screen. These estimates are based on the default Mesh Data settings.

Change the view to clearly show the topology on the hub:

1. Click Hide all geometry objects .

2. Turn off the visibility of Layers > Shroud Tip to hide the topology on the shroud tip.

3. Right-click a blank area in the viewer, and click Predefined Camera > View From +X from the shortcut

menu.

The heavy lines in Figure 2.1: ATM Topology and 2D Mesh on the Hub (p. 8) indicate the topology

lines; the thinner lines show the 2D mesh for the hub. Note that the 3D mesh does not yet exist.

Figure 2.1: ATM Topology and 2D Mesh on the Hub

This completes the topology definition.


The Mesh Data settings control the number and distribution of mesh elements.

1. Set Method to Global Size Factor .

2. Set Size Factor to 1.0 .

In the status bar in the bottom-left corner of ANSYS TurboGrid, you can see that the number of

mesh nodes is on the order of 90000.


Layers are constant-span surfaces. You can display the topology and control the mesh on a layer. You

have already seen the hub layer in Figure 2.1: ATM Topology and 2D Mesh on the Hub (p. 8). At this

point, there are two layers: Layers > Hub, and Layers > Shroud Tip .

Before generating the 3D mesh, it is recommended that you check the mesh quality on the layers, es-

pecially the hub and shroud tip layers. By correcting any mesh problems early, you can save time by

minimizing the number of times you generate the full 3D mesh.


Rotor 37

If the topology were grossly skewed or distorted on the hub or shroud tip layer, the Layers object

would be shown with red text in the object selector. Since the Layers object is shown in black text,

the mesh contains no regions with high skew on the hub and shroud tip layers.


Now that the topology has been defined and the mesh quality is acceptable on all layers, generate the

mesh:

1. Click Insert > Mesh.

After the mesh has been generated, 3D mesh measures are available. You will check these in the

next section. Mesh visualization objects, listed under 3D Mesh , are also available. By default, one

of these objects, called Show Mesh , is shown in the viewer. You can alter this object or view

other 3D Mesh objects to inspect different parts of the mesh. Later in this tutorial, you will view

some of the objects listed under 3D Mesh .

2. Turn off the visibility of 3D Mesh > Show Mesh so that you can see the mesh without obstruction.

2.9. Looking at Mesh Data Values

Now that you have generated the mesh, the Mesh Data editor tabs display information about the

mesh. In the following steps, you will examine the number and distribution of elements from hub to

shroud tip and from shroud tip to shroud.

1. Open Mesh Data .

2. Click the Passage tab.

Look in the Spanwise Blade Distribution Parameters frame. Method is set to Proportionalwith a factor of 1.0. The other boxes in the frame are disabled, but show the current value for each

option that ANSYS TurboGrid has calculated.

You can see that # of Elements is 22 .

3. Click the Shroud Tip tab.

Look in the Shroud Tip Distribution Parameters frame. Method is set to Match Expansionat Blade Tip . You can see that the number of elements from shroud tip to shroud is 5.

2.10. Analyzing the Mesh Quality

Now that the mesh has been generated, 3D mesh measures are available. These are analogous to the

2D mesh measures that are calculated on layers. As for the 2D mesh measures, the 3D mesh measures

have quality criteria set in the Mesh Analysis > Mesh Limits object.

When any mesh measure fails to meet the criteria, Mesh Analysis > Mesh Statistics (Error)will appear in red text in the object selector. With default criteria, there will almost always be some

mesh elements that fall outside the criteria; a visual inspection of the mesh measures is usually required

to determine whether the mesh is satisfactory.

Check the 3D mesh statistics:

1. For a visual frame of reference, ensure that Layers > Hub and Layers > Shroud Tip are visible.



Analyzing the Mesh Quality

2. Open Mesh Analysis or Mesh Analysis > Mesh Statistics .

The mesh statistics shown here may differ slightly from what you see:

In this case, Maximum Element Volume Ratio and Maximum Edge Length Ratio do

not meet the criteria. Not all of the mesh statistics carry the same importance. For example, it is

necessary to have a mesh with no negative volumes. Generally, poor angles should also be fixed,

but the Maximum Element Volume Ratio and Maximum Edge Length Ratio values

should be judged based on your requirements.

3. Double-click Maximum Element Volume Ratio , or select Maximum Element Volume Ratioand then click Display.

This will display the elements that have an element volume ratio greater than 2 (the default criterion).

A built-in volume object, Mesh Analysis > Show Limits , automatically changes its definition

and appears in the viewer. This volume object includes the mesh elements that fail to meet the

criteria for the selected mesh measure.

4. Double-click Maximum Edge Length Ratio to cause the Show Limits object to display the

elements that have an edge length ratio greater than 100 (the default criterion).

The Mesh Analysis > Show Limits object appears near the blade surface. This is normal,

and not necessarily a problem.

5. In the Mesh Statistics dialog box, click Close.

6. Turn off the visibility of Mesh Analysis > Show Limits .

2.11. Visualizing the Hub-to-Shroud Element Distribution

To demonstrate the use of the 3D Mesh visualization objects, look at the mesh distribution from hub

to shroud as follows:

1. Click Unhide geometry objects .

2. Turn off the visibility of the following objects:


Rotor 37

• Geometry > Blade Set > Blade 1

• Layers > Hub

• Layers > Shroud Tip

3. Turn on the visibility of the following objects:

• 3D Mesh > LOWBLADE

• 3D Mesh > HIGHPERIODIC.

4. Observe the element distribution from hub to shroud tip and from shroud tip to shroud.

See Figure 2.2: Hub-to-Shroud Element Distribution (p. 11).

Figure 2.2: Hub-to-Shroud Element Distribution



Visualizing the Hub-to-Shroud Element Distribution

2.12. Observing the Shroud Tip Mesh

A mesh interface exists in the shroud tip gap. In order to see this interface:

1. Turn on the visibility of 3D Mesh > SHROUD TIP.


3. Zoom in to view the mesh on the shroud tip.

Figure 2.3: Surface Group: Tip Near Trailing Edge (p. 12) shows this mesh at the trailing edge of

the blade. Note how the nodes do not line up along the middle of the blade, due to the default

use of a general grid (GGI) interface along the shroud tip of the blade.

Figure 2.3: Surface Group: Tip Near Trailing Edge

4. Turn off the visibility of 3D Mesh > SHROUD TIP.

5. Click Unhide geometry objects .

2.13. Examining the Mesh Qualitatively

You will now examine the mesh qualitatively using a turbo surface. Change the Show Mesh turbo

surface so that it appears on the hub, and color it to show the variation in Edge Length Ratio (a

variable that was computed at the time the mesh was generated):

1. Turn on the visibility of 3D Mesh > Show Mesh .

2. Open 3D Mesh > Show Mesh .

3. Leave Variable set to K.

K is equal to the node number in the spanwise direction, ranging from 1 at the hub to a positive

integer value at the shroud.

4. Set Value to 1.

This will cause the turbo surface to appear on the hub.

5. Click the Color tab.

6. Set Mode to Variable .

7. Set Variable to Edge Length Ratio .


Rotor 37

8. Set Range to Local .

This will cause the range of colors in the color map to be distributed over the range of values found

on the turbo surface, rather that over the global range or a user-defined range.

9. Click the Render tab.

10. Ensure that Draw Faces is selected.

11. Click Apply.

12. To avoid visual conflicts between the turbo surface and the hub, which are coincident, turn off the

visibility of Geometry > Hub.

Note that you can edit the rendering properties of the hub to achieve a similar result. The advantage

of using a turbo surface is that you can redefine its location. For example, you could change the value

of K in the current turbo surface to see Edge Length Ratio on a different nodal plane.

Note

You can create new turbo surfaces. To begin the process of creating a new turbo surface,

click Insert > User Defined > Turbo Surface.

Note

To show distinct color bands, you could make a contour plot object that applies to an existing

locator (geometric surface, turbo surface, or other graphic objects that involve surfaces). To

begin the process of creating a contour plot, ensure that you have a suitable locator already

defined, then click Insert > User Defined > Contour.

Tip

For objects that are colored by a variable, it is best to view them with lighting turned off, so

that the colors are not altered according to the angle of view. The lighting is controlled by

a setting on the Render tab.

2.14. Creating a Legend

In the previous section, you modified a turbo surface by coloring it according to Edge Length Ratio .

To reveal the color map used to match values of Edge Length Ratio with particular colors, create

a legend for the turbo surface:

1. Click Insert > User Defined > Legend.

2. Click OK to accept the default name.

3. Set Plot to TURBO SURFACE:Show Mesh.

4. Set Title Mode to Variable and Location .

5. Click Apply.



Creating a Legend

A legend appears in the viewer, showing the correspondence between values of Edge LengthRatio and colors for the Show Mesh object.

You may want to modify 3D Mesh > Show Mesh to plot it on different locations, or to color it by

different variables. The legend will be updated automatically whenever you make changes to the turbo

surface.


Save the mesh:

1. Click File > Save Mesh As.

2. Ensure that File type is set to ANSYS CFX.

3. Set Export Units to cm.

4. Set File name to rotor37.gtm .

5. Ensure that your working directory is set correctly.

6. Click Save.


If you want to revisit this mesh at a later date, save the state:

1. Click File > Save State As.

2. Enter an appropriate state file name.

3. Click Save.


Rotor 37

Chapter 3: Steam Stator







3.6. Reviewing the Mesh Quality on the Hub and Shroud Layers


3.8. Analyzing the Mesh



This tutorial teaches you how to:

• Import hub, shroud, and blade geometry from individual curve files.

• Change the method of constructing the hub and shroud curve types.

• Make colored surfaces to show variations in mesh measures (such as Minimum Face Angle ).

As you work through this tutorial, you will create a mesh for a blade passage of a steam stator. A typical

blade passage is shown by the black outline in the figure below.



The stator contains 60 blades distributed about the Z-axis. Within the blade passage, the maximum

diameter of the shroud is approximately 97.5 cm.


If this is your first tutorial, review the topics in Introduction to the ANSYS TurboGrid Tutorials (p. 1).


1. Prepare the working directory using the files in the examples/stator directory.





In the first tutorial, you loaded a BladeGen.inf file in order to specify the machine data (# of blade

sets, rotation axis, and units) and curve files. In this tutorial, you will enter such data manually using

the Load Curves command.


Steam Stator

3.3.1. Loading the Curves

Load the curve files for the steam stator as follows:

1. Click File > Load Curves to open the Load TurboGrid Curves dialog box.

The Load TurboGrid Curves dialog box appears. ANSYS TurboGrid fills in the names of the curve

files based on the files that are present in the working directory; The first .crv or .curve file

found that has a name containing “hub”, ”shroud”, or “blade”/”profile” is selected as the hub,

shroud, or blade file, respectively.

2. Set # of Bladesets to 60 .

3. Set Rotation > Method to Principal Axis and Axis to Z.

4. Set Coordinates and Units > Coordinates to Cartesian and Length Units to cm.

These units are used to interpret the data in the curve files.

5. Ensure that, under TurboGrid Curve Files, Hub is set to ./hub.curve , Shroud is set to

./shroud.curve , and Blade is set to ./profile.curve .




6. Click OK to save the settings.

The progress bar at the bottom right of the screen shows the geometry generation progress. After the

geometry has been generated, you can see the hub, shroud, and blade for one passage. Along the

blade, you can see the leading and trailing edge curves (green and red lines, respectively). Near the

blade, you can see the inlet and outlet markers (white octahedrons).

• Rotate the geometry into the position shown in Figure 3.1: Incorrect Hub and Shroud Representations (p. 18).

Figure 3.1: Incorrect Hub and Shroud Representations

As shown in Figure 3.1: Incorrect Hub and Shroud Representations (p. 18), the hub and shroud are

greatly distorted. This is the result of using spline curves to construct the hub and shroud based on

relatively few data points. This problem will be corrected in the next section.

3.3.2. Setting the Curve Type

Set the method of constructing the hub and shroud as follows:


2. Set the Curve Type to Piece-wise linear .

3. Click Apply.

4. Set Shroud in the same way.


Steam Stator

Intermediate points were created for the outlet. Because these points can have a dependence on

the shapes of the hub and shroud curves, and because the latter were changed, regenerate the

outlet points:

5. Open Geometry > Outlet .

6. Click Generate intermediate points .

7. When you are notified that intermediate points will be deleted, click Yes to continue.

Note

Note that the intermediate outlet points disappear. This happens because the regenerated

set of outlet points happens to contain no intermediate points.

This completes the geometry definition.


For this steam stator mesh, ATM Optimized is an appropriate topology choice.

1. Click Hide all geometry objects to turn off the visibility of the geometry.



This provides access to the newest topology method. The other option, Traditional withControl Points , provides access to the legacy topology methods.

4. Click Apply to set the topology.


After a short time, the topology appears on the hub and shroud as a structure of thick lines. Thinner

lines show a preview of the mesh elements.


Note

It may be useful to keep the same topology when studying a range of blade geometries, or

the same blade on different computers. To keep the same topology, use the Manual (Ad-

vanced) setting for the topology. For more information on the Manual (Advanced) setting,

see Advanced Topology Control.


1. Set Method to Global Size Factor .

2. Set Size Factor to 1.0 .



Reviewing the Mesh Data Settings


Before generating the 3D mesh, it is recommended that you check the mesh quality on the layers. By

correcting any mesh problems early, you can save time by minimizing the number of times you generate

the full 3D mesh.

If the topology were grossly skewed or distorted on the hub or shroud layer, the Layers object would

be shown with red text in the object selector. Since the Layers object is shown in black text, the mesh

contains no regions with high skew on the hub or shroud.



mesh:

• Click Insert > Mesh.

ANSYS TurboGrid automatically generates the recommended number of layers before the mesh is

generated. This default behavior can be disabled by editing the Layers object by clearing Automat-

ically generate required layers at mesh creation on the Advanced Parameters tab.

A turbo surface of constant “K” (a nodal coordinate) appears. This surface is listed in the object selector

as 3D Mesh > Show Mesh . Later in this tutorial, you will change the location and coloring of this

surface to explore the mesh.



1. Open Mesh Analysis .

The mesh statistics shown here may differ slightly from what you see.

2. Double-click Maximum Element Volume Ratio to display the elements that have an element

volume ratio greater than 2 (the default criterion set in the Mesh Analysis > Mesh Limits object).


Steam Stator

The Mesh Analysis > Show Limits volume object shows the areas in the mesh that do not

meet the criteria. To improve the element volume ratio in this part of the mesh, you could increase

the mesh density. However, it is not necessary to do this for the purposes of this tutorial.

3. Double-click Maximum Edge Length Ratio to display the elements that have an edge length ratio

greater than 100 (the default criterion).

The Mesh Analysis > Show Limits object appears mainly on the blade surface. This is normal,

and not necessarily a problem.

4. In the viewer, right-click the Show Limits object and click Set Turbosurface Position from the

shortcut menu.

The constant-“K” turbosurface (3D Mesh > Show Mesh ) moves to the location where you right-

clicked to invoke the shortcut menu.

Another way to move this object is by editing its definition in the object editor.

5. Close the Mesh Statistics dialog box.

6. Turn off the visibility of Mesh Analysis > Show Limits .

3.8.1. Examining the Mesh Qualitatively

The predefined surfaces found under the 3D Mesh object in the object selector are useful for showing

variations in the mesh statistics.

In the following section, you will color 3D Mesh > Show Mesh by Minimum Face Angle . You will

then create a legend for that object.

3.8.1.1. Editing a Turbo Surface

Turbo Surfaces can be created by selecting Insert > User Defined > Turbo Surface. In this case, you

will simply edit the predefined turbo surface.

1. Open 3D Mesh > Show Mesh .

2. Leave Domains, Variable, and Value unchanged.

3. Click the Color tab and set Mode to Variable .

4. Set Variable to Minimum Face Angle .

5. Set Range to Local .

This will cause the range of colors in the color map to be distributed over the range of values found

on the turbo surface, rather that over the global range or a user-defined range.

6. Click the Render tab.

7. Ensure that Draw Faces is selected.

8. Click Apply to apply the changes to the turbo surface.



Analyzing the Mesh

3.8.1.2. Creating a Legend

To illustrate the scale of the Minimum Face Angle variable, create a legend for the turbo surface:

1. Click Insert > User Defined > Legend.


3. Set Plot to TURBO SURFACE:Show Mesh.

4. Set Title Mode to Variable and Location .

5. Leave the remaining settings unchanged.

6. Click Apply to create the legend.


Save the mesh:




4. Set File name to steam_stator.gtm .


6. Click Save.





3. Click Save.


Steam Stator

Chapter 4: Radial Compressor












• Set machine data and load curve files independently.

• Specify a “cut-off or square” edge on a blade.

• Choose an appropriate topology family under ATM Topology.

As you work through this tutorial, you will create a mesh for a blade passage of a radial compressor

blade row using the Automatic Topology and Meshing (ATM Optimized) feature. A typical blade passage

is shown by the black outline in the figure below.



The blade row contains 18 blades that revolve about the negative Z-axis. The blades have cut-off trailing

edges. Within the blade passage, the maximum diameter of the shroud is approximately 125 mm.




1. Prepare the working directory using the files in the examples/radcomp directory.





Radial Compressor


In the Rotor 37 tutorial, you loaded a BladeGen.inf file in order to specify the machine data (# of

blade sets, rotation axis, and units) and the hub, shroud, and blade curve files. In the Steam Stator tu-

torial, you entered the same data using the Load Curves command. In this tutorial, you will define the

machine data and curve files individually, by editing the corresponding geometry objects.

4.3.1. Defining the Machine Data

Set up the Machine Data object, which contains basic information about the geometry:

1. Open Geometry > Machine Data .

2. Set # of Bladesets to 9.

3. Set Base Units to mm.

4. Click Apply to save the settings.

4.3.2. Defining the Hub


2. Set Length Units to mm.

3. Ensure that File Name is set to ./hub.crv from your working directory.




4. Click Apply.

4.3.3. Defining the Shroud

1. Open Geometry > Shroud .


3. Ensure that File Name is set to ./shroud.crv from your working directory.

4. Click Apply.

Note

If you had loaded the BladeGen.inf file, the Curve Type settings for the Hub and

Shroud objects would have been set to Piece-wise linear instead of the default:

Bspline . Either setting will work for this geometry.

At this point, the entire hub and shroud surfaces are shown. After a blade is defined (in the next step),

the hub and shroud will be trimmed to show only one passage.

Figure 4.1: Hub and Shroud of Radial Compressor

4.3.4. Defining the Blade

1. Open Geometry > Blade Set > Blade 1 .

2. Ensure that File Name is set to ./profile.crv .


4. Set Geometric Representation > Method to Specify .


Radial Compressor

5. Set Geometric Representation > Lofting to Spanwise .

6. Set Geometric Representation > Curve Type to Piece-wise linear .

7. Set Geometric Representation > Surface Type to Ruled .

8. Under Trailing Edge Definition, select Cut-off or square.

This will more accurately represent the blade at the trailing edge. In addition, for geometry with

splitter blades, ATM Optimized topology only supports blades with these settings in release 14.5.

You will be using the ATM Optimized topology feature later on in this tutorial.

9. Click Apply.

The progress bar at the bottom right of the screen shows the geometry generation progress. After the

geometry has been generated, you can see the hub, shroud, and blade for one passage. Along the

blade, you can see the leading and trailing edge curves (green and red lines, respectively).




4.3.5. Defining the Splitter Blade

1. Right-click Geometry > Blade Set and select Insert > Blade.


3. Set Blade Number to 2.

4. Click Apply.

After the geometry has been generated, you can see the main and splitter blades for one passage.


The ATM Optimized feature is a method for creating a mesh. It enables you to control the global mesh

size as well as the mesh size at the boundary layer. This method of meshing is generally easier to use

than the traditional topology methods. It also tends to result in better mesh quality. For details on the

ATM Optimized method, see ATM Optimized Topology in the TurboGrid User's Guide. In this tutorial, you

will manually choose a set of ATM topology templates, called a topology family.



3. Click the Topology Viewer tab.

4. Browse through ATM Topology > Method.

ATM Topology > Method provides a list of topology families from which you can manually choose.

When you mouse over or cursor through the list, a picture of the highlighted topology family and

a description of the type of blade that the family best fits are shown in the topology viewer. Since

the present geometry has a splitter blade, the Single Splitter topology family is the most appro-

priate choice.

5. Select ATM Topology > Method > Single Splitter.



After a short time, the topology is generated.



Leave the Mesh Data settings at their default values.


Radial Compressor

The ATM Optimized method automatically computes a default mesh and sets the base mesh dimensions.

Each unique mesh dimension has an edge refinement factor that is multiplied by the base mesh dimen-

sion and global size factor to determine the final mesh size. The overall mesh size is controlled using

the Method setting. Setting the Method to Target Passage Mesh Size enables you to specify

a Node Count. Using this method specifies an approximate mesh size (in nodes) and lets ANSYS Tur-

boGrid compute the mesh dimensions automatically. Setting the Method to Global Size Factorenables you to specify a Size Factor. Increasing this factor will increase the overall mesh size, and de-

creasing it will decrease the overall mesh size. The change is not linear.

The Boundary Layer Refinement Control settings affect the mesh in the O-Grid region around the

blade.

• The Proportional Refinement setting controls the number of elements across the boundary layer in

proportion to the specified Factor Ratio. ANSYS TurboGrid computes the edge refinement factor as the

Factor Ratio times the global size factor. Increasing or decreasing the Factor Ratio will effectively increase

or decrease the expansion rate, respectively.

• The Cutoff Edge to Boundary Layer setting controls the number of elements along the cut-off edge in

proportion to the specified Factor. The number of elements along the cut-off edge is also proportional



Reviewing the Mesh Data Settings

to the number of elements across the boundary layer. Increasing or decreasing the Factor will effectively

increase or decrease the number of elements along the cut-off edge, respectively.

• The Near Wall Element Size Specification setting controls the method by which the near-wall node

spacing is specified on the Passage, Hub Tip, and Shroud Tip tabs. The near-wall node spacing is the

distance between a wall (for example, hub, shroud, or blade) and the first layer of nodes from the wall.

The available Method options are:

– Y Plus — The y+ method sets the near-wall spacing to a target value, y+, and in relation to a set

Reynolds number.

– Absolute — The Absolute method enables you to set the near-wall spacing directly on the Passage,

Hub Tip, and Shroud Tip tabs.

• The Inlet Domain and Outlet Domain check boxes allow you to generate the inlet and outlet domains

as part of the mesh. Settings that affect these grid regions are found on the Inlet/Outlet tab.

Selecting the Lock mesh size check box forces the total number of nodes and elements to remain

constant.

For a description of the available options, see Mesh Data and ATM Optimized Topology in the TurboGrid

User's Guide.



mesh:




• Open Mesh Analysis .

The mesh statistics are in reasonable shape for a coarse mesh.


Radial Compressor

You can double-click one of the items in red to see the locations in the mesh where the statistics fail

to meet the criteria set in Mesh Analysis > Mesh Limits . Further improvements to the mesh are

possible, but are beyond the scope of this tutorial.


Save the mesh:




4. Set File name to radial_compressor.gtm .


6. Click Save.





3. Click Save.



Saving the State (Optional)


Chapter 5: Axial Fan Using ATM Optimized Topology






5.5. Increasing the Mesh Density


5.7. Using the Locking Feature

5.8.The Y+ Functionality

5.9. Using Local Mesh Refinement


5.11. Adding Inlet and Outlet Domains

5.12. Analyzing the New Mesh




• Switch to a Meridional (A-R) projection in the viewer.

• Change the shape and position of the Inlet and Outlet geometry objects which bound the blade

passage in the streamwise direction.

• Use the ATM Optimized feature to generate and customize a mesh as desired.

• Extend the mesh by adding inlet and outlet domains.

This tutorial is very similar to Axial Fan Using Traditional Topology (p. 43). The notable difference is the

use of the ATM Optimized feature to generate and control the mesh. As you work through this tutorial,

you will create a mesh for a blade passage of a fan. A typical blade passage, inlet domain, and outlet

domain, are shown by the black outline in the figure below.



The fan contains 10 blades that revolve about the negative Z-axis. A clearance gap exists between the

blades and the shroud, with a width of 5% of the total span. The shroud diameter is approximately 26.4

cm.

Let the mesh contain an inlet domain and an outlet domain.




1. Prepare the working directory using the files in the examples/fan directory.





To obtain the basic geometry, you will load a BladeGen.inf file. After inspecting the geometry and

improving the shape of the inlet and outlet, you will finish defining the geometry by creating the required

gap between the blade and the shroud.


Axial Fan Using ATM Optimized Topology

Load the BladeGen.inf file, then inspect the geometry by viewing it in axial-radial coordinates:



3. Right-click a blank area in the viewer, and click Transformation > Meridional (A-R) from the shortcut

menu.

The passage inlet, which appears in the object selector as Geometry > Inlet , is the upstream end

of the blade passage (but not necessarily the upstream end of the mesh, since, as you will see in this

tutorial, you can add an inlet domain upstream of the passage inlet). The passage inlet is generated by

revolving a curve, which is defined in an axial-radial plane, about the machine axis. That curve, in turn,

is generated according to a set of points, known here as inlet points. These points appear as white oc-

tahedrons in the viewer. The passage outlet is analogous to the passage inlet, and is downstream of

the blade passage.

Notice that, in this case, there are two inlet points and they are located at different distances from the

blade. In order to obtain a high-quality mesh topology for the blade passage, the inlet points should

be repositioned.

Reposition the inlet and outlet points as follows, and observe the movement of the inlet and outlet

points in the viewer:

1. Open Geometry > Inlet .

2. Select Low Hub Point , then set Method to Set A and Location to -0.008 .

3. Click Apply.

4. Select Low Shroud Point , then set Method to Set A and Location to 0.002 .

5. Click Apply.





7. Select Low Hub Point , then set Method to Set A and Location to 0.03 .

8. Click Apply.


10. Click Apply.


be shortened to 95% of its original span because the gap width is 5% of the total span, as specified in

the problem description.




4. Click Apply.


To generate an effective mesh normally requires a great deal of work. However, using the ATM Optimized

setting, this work is significantly reduced. Once the setting is implemented, the Topology Set must

be activated.

1. Right-click a blank area in the viewer, and click Transformation > Cartesian (X-Y-Z) from the shortcut

menu.


This gives you an unobstructed view of the topology, and later the mesh.





By default, the Topology Set is suspended along with several other items in the object selector.

Turning off Suspend Object Updates activates these items and defines the mesh topology. ANSYS

TurboGrid takes a few moments to complete calculations, then displays the proposed topology in

the viewer. The total number of nodes and total number of elements are also displayed in the user

interface. These are updated automatically after the changes to the mesh topology are applied.





This next section will demonstrate your capability to control the mesh size. This can be done in several

ways:

• Changing the total passage mesh size.

• Changing the global size factor.

• Using proportional refinement in the boundary layer.

• Changing the edge refinement on a specific edge, including within the boundary layer.

We will demonstrate how to use the global size factor to change the overall mesh size and how to

change the refinement in the boundary layer, with and without proportional refinement. For the other

options, please see ATM Optimized Topology in the TurboGrid User's Guide.

Apply these settings:

1. Open Mesh Data .

2. On the Mesh Size tab, set Method to Global Size Factor .

3. Set the Size Factor to 1.2 .

To increase the resolution of the mesh, and effectively capture more data, an overall increase in

mesh size is useful.

4. Set Boundary Layer Refinement Control > Method to Proportional to Mesh Size .

5. Set the Factor Ratio to 2.0 .

6. Click Apply.

Observe that the number of nodes and the mesh size at the boundary layer is far greater. With

proportional refinement enabled, the relationship between the height of the first element in the

boundary layer and the global size factor should be approximately inversely proportional (that is,

an increase in the global size factor will cause a decrease in the element height). With proportional

refinement disabled, the number of elements in the boundary layer will vary proportionally to the

global size factor. Right-click a blank area in the viewer, and select Predefined Camera > Isometric

View (X Up).

7. Change Boundary Layer Refinement Control > Method to Edge Refinement Factor .

8. The Edge Refinement Factor option is selected, and Parameters > Factor is already set. The

value of this factor was chosen by default to maintain a similar mesh topology as when Proportionalto Mesh Size was selected. The edge refinement factor is defined as the global size factor multiplied

by the proportional refinement factor.

9. Set Parameters > Factor to 2.0 .

10. Click Apply.

Observe that the total number of elements has decreased significantly compared to when Propor-tional to Mesh Size was selected. The largest concentration of nodes is still located at the



Increasing the Mesh Density

boundary layer, due to the Edge Refinement Factor . For more information on these features,

see ATM Optimized Topology in the TurboGrid User's Guide.


You will now generate the mesh to see the changes you have made:

1. Click Mesh to generate the mesh.

A K-Plane is displayed by default. This shows the 2D mesh on a layer. The plane can be moved in

the spanwise direction by holding Ctrl + Shift and dragging using the left mouse button.

2. Enable 3D Mesh > HIGHBLADE, 3D Mesh > HUB, 3D Mesh > LOWBLADE and 3D Mesh > SHROUDin the object selector.

Observe that the increase in mesh size near the boundary layer also occurs in the spanwise direction,

as can be seen in Figure 5.1: Snapshot of Mesh at Blade-Hub Intersection (p. 38).

Figure 5.1: Snapshot of Mesh at Blade-Hub Intersection

The mesh size in the spanwise direction is automatically changed depending on the global size factor

and the mesh size at the boundary layer. It can also be specified. You are going to increase the mesh

size in the spanwise direction by a factor of 1.5:

1. Open Mesh Data .

2. On the Passage tab, set Spanwise Blade Distribution Parameters > Factor to 1.5 .

Note that the greyed out # of Elements field indicates a total of 54 elements in the spanwise dir-

ection. This will now increase.



3. Click Apply.

The number of elements has increased to 100. This is roughly an increase by a factor of 1.5.

5.7. Using the Locking Feature

Note

This section is for information only. Do not use the locking feature in this tutorial.

When you are using ANSYS Workbench, ANSYS TurboGrid allows you to use the Lock mesh size feature.

Once activated, the total number of nodes and elements will remain constant. This holds true even if

the geometry of the blade is changed. The size of the mesh elements will be readjusted, but the total

number will not be changed. The feature can be found under the Mesh Size tab, under Mesh Datain the object selector. For more details, see Lock Mesh Size Check Box (ATM topology only) in the Tur-

boGrid User's Guide.

5.8. The Y+ Functionality

Another method of controlling the mesh size at the boundary layer is specifying the y+ height and

Reynolds number. This option lets you specify the maximum y+ height for the blade, which is then

used to calculate the edge refinement factor. The actual first element offset will not be consistent across

the boundary layer, although it should be equal or less than the maximum specified. The edge refinement

calculation is only an approximation.

You will enable the option for y+, then set the offset to 15. You will also set the Reynolds number to

500,000.

1. Open Mesh Data .

2. Set Boundary Layer Refinement Control > Near Wall Element Size Specification > Method to y+ .

3. Set Reynolds No. to 5e5 .

4. Change Boundary Layer Refinement Control > Method to First Element Offset .

The field for specifying Offset Y+ is enabled.

5. Set Parameters > Offset Y+ to 15 .

6. Click Apply.

You should see an increase in the mesh size at the boundary layer. You will generate the mesh to

inspect your changes.


The latest mesh will have very small elements near the boundary layer. This can be seen in Fig-

ure 5.2: Mesh at Blade-Hub Intersection After Y+ Settings (p. 40).



The Y+ Functionality

Figure 5.2: Mesh at Blade-Hub Intersection After Y+ Settings

5.9. Using Local Mesh Refinement

The ATM feature also allows for local mesh refinement. This is especially useful when attempting to

manipulate the mesh near a specific boundary without tampering with the surroundings. Once local

mesh refinement has been implemented, changing the global size factor will affect the localized area

as well. However, the locally refined mesh will remain discernible from its surroundings. You will imple-

ment this feature at the shroud boundary, upstream of the blade as indicated in the figure below. The

local mesh size will be increased by 100%.

1. Click Hide all mesh objects .

To be able to see which boundary to modify, it's best to hide the currently generated mesh. Ulti-

mately, only the topology will be visible when refinements are made.

2. Right-click the edge of the shroud tip layer, marked A in Figure 5.3: Edge to be Refined in Shroud Tip

Layer (p. 41), and select Increase Edge Refinement > 100%.

After a few seconds of processing, you should observe the mesh size increasing by a factor of 2 at

the edge you selected. Only topologically parallel edges will be affected by this change.



Figure 5.3: Edge to be Refined in Shroud Tip Layer



Inspect the mesh quality of the 3D mesh:


The mesh statistics indicate only two items that ANSYS TurboGrid feels require your attention —

these are flagged because of the built-in parameters in ANSYS TurboGrid. Since the statistics listed

as being bad have low percentages, you can safely ignore the warning.






Analyzing the Mesh


As specified in the problem description, the mesh should contain an inlet domain and an outlet domain.

1. Open Mesh Data .

2. On the Mesh Size tab, select Inlet Domain and Outlet Domain.

3. Click Apply.



1. Open Mesh Analysis . Note that the Maximum Edge Length Ratio mesh measure is extremely

large. By displaying this mesh measure, you will see that some of the mesh elements that exceed the

criterion are at the inlet where the mesh meets the rotation axis. This is to be expected wherever the

hub reaches the axis of rotation because at these locations the element edges have zero length.

2. View the mesh on the inlet and outlet (not the passage inlet and outlet, but the inlet and outlet of the

entire mesh) by turning on the visibility of the corresponding 3D Mesh objects.


Save the mesh:




4. Set File name to fanATM.gtm .


6. Click Save.





3. Click Save.



Chapter 6: Axial Fan Using Traditional Topology








6.7. Adding Intermediate Layers




6.11. Regenerating the Mesh





• Switch to a Meridional (A-R) projection in the viewer.

• Change the shape and position of the Inlet and Outlet geometry objects which bound the blade

passage in the streamwise direction.

• Specify the use of a General Grid Interface on the periodic surfaces of the blade passage.

• Extend the mesh by adding inlet and outlet domains.

As you work through this tutorial, you will create a mesh for a blade passage of a fan. A typical blade

passage, inlet domain, and outlet domain, are shown by the black outline in the figure below.



The fan contains 10 blades that revolve about the negative Z-axis. A clearance gap exists between the

blades and the shroud, with a width of 5% of the total span. The shroud diameter is approximately 26.4

cm.

Let the mesh contain an inlet domain and an outlet domain.




1. Prepare the working directory using the files in the examples/fan directory.





To obtain the basic geometry, you will load a BladeGen.inf file. After inspecting the geometry and

improving the shape of the inlet and outlet, you will finish defining the geometry by creating the required

gap between the blade and the shroud.


Axial Fan Using Traditional Topology

Load the BladeGen.inf file, then inspect the geometry by viewing it in axial-radial coordinates:




menu.

The passage inlet, which appears in the object selector as Geometry > Inlet , is the upstream end

of the blade passage (but not necessarily the upstream end of the mesh, since, as you will see in this

tutorial, you can add an inlet domain upstream of the passage inlet). The passage inlet is generated by

revolving a curve, which is defined in an axial-radial plane, about the machine axis. That curve is, in

turn, generated according to a set of points, known here as inlet points. These points appear as white

octahedrons in the viewer. The passage outlet is analogous to the passage inlet, and is downstream of

the blade passage.

Notice that, in this case, there are two inlet points and they are located at different distances from the

blade. In order to obtain a high-quality mesh topology for the blade passage, the inlet points should

be repositioned.

The outlet points should also be repositioned; they should be moved closer to the blade to reduce the

aspect ratio of mesh elements immediately downstream of the blade trailing edge, as shown in Fig-

ure 6.1: Effect of Moving Passage Outlet Towards Blade (p. 46).




Figure 6.1: Effect of Moving Passage Outlet Towards Blade

Reposition the inlet and outlet points as follows, and observe the movement of the inlet and outlet

points in the viewer:


2. Select Low Hub Point , then set Method to Set A and Location to -0.008 .

3. Click Apply.


5. Click Apply.


7. Select Low Hub Point , then set Method to Set A and Location to 0.03 .

8. Click Apply.


10. Click Apply.


be shortened to 95% of its original span because the gap width, as specified in the problem description,

is 5% of the total span.






4. Click Apply.


For this fan mesh, H/J/C/L-Grid is an appropriate topology choice.


2. Set Topology Definition > Placement to Traditional with Control Points .

This provides access to the legacy topology methods. The other option, ATM Optimized , provides

access to the newest topology method.

3. Set Topology Definition > Method to H/J/C/L-Grid .

The H/J/C/L-Grid method causes TurboGrid to choose an H-Grid, J-Grid, C-Grid, L-Grid, or a combin-

ation of these, based on heuristics. To override TurboGrid’s choice, you may select one of the other

menu options. Normally, you would choose the H/J/C/L-Grid method for the first attempt at

a mesh, then change the method if required. For details on the H/J/C/L-Grid method, see

H/J/C/L Topology Definition in the TurboGrid User's Guide.

4. Ensure that Include O-Grid is selected.

This adds an O-Grid around the blade to increase mesh orthogonality in that region.

5. Set Include O-Grid > Width Factor to 0.3 .

This will specify the O-Grid thickness to be approximately equal to 30% of the average blade width.

This value is smaller than the default value of 0.5 because of the relatively short distance between

the blades, compared to the blade thickness, at the hub. In general, a suitable value of the O-Grid

thickness depends on the blade geometry and topology type. Trial-and-error adjustments are

sometimes required to establish a good value when creating the first mesh for a particular blade.

6. Set One-to-one Interface Ranges > Periodic to None.

This allows the nodes to be misaligned across the periodic interface; the nodes on one periodic

surface are not required to connect in a one-to-one fashion with the nodes on the other periodic

surface. When you set up the resulting mesh in a CFD simulation, a General Grid Interface will be

required to connect the periodic surfaces. While such an interface may require more processing

time and may be less accurate than a one-to-one interface, the benefit of using a GGI interface is

that the passage mesh can be made with less skew. This setting is often beneficial when the blade

has a high stagger angle.

7. Leave Periodicity > Projection set to Float on Surface .

This allows the periodic surface of the mesh to deviate from the geometric periodic surface, in order

to improve mesh skewness properties along the periodic boundary. The topology on a given layer

floats on the layer, but is not constrained to stop exactly on the intersection of the layer with the

geometric periodic surface.







10. Click Freeze to freeze the topology settings.

It is recommended that you freeze the topology after you specify and generate it. This prevents

the settings on the Advanced Parameters tab of Topology Set > Blade 1 from inadvertently

changing due to changes to the geometry or the topology distribution. For example, an adjustment

to the position of an inlet point could cause a change to the number of topology blocks from the

blade to the inlet.


1. Set Method to Topology Block Edge Split .

2. Set # of Elements to 2.

As prescribed in the problem description, the mesh should contain an inlet domain and an outlet domain.

For now, leave the Inlet Domain and Outlet Domain check boxes cleared; you will select these check

boxes later in this tutorial. The inlet domain contains some degenerate elements where the hub reaches

zero radius. The degenerate elements affect the mesh statistics, and make it more difficult to analyze

the quality of the rest of the mesh.


Before generating the 3D mesh, it is recommended that you check the mesh quality on the layers, es-

pecially the hub and shroud tip layers. By correcting any mesh problems early, you can save time by

minimizing the number of times you generate the full 3D mesh.

For a more detailed analysis of the mesh quality on a layer, open the layer object and read the list of

mesh measures. If the mesh measures are not shown, select Refined Mesh Visibility and click Apply.

The mesh measures show the extreme values for the mesh elements. If any of the mesh measures are

considered “bad”, they are listed in red text. The criteria for “bad” mesh elements are set in the MeshAnalysis > Mesh Limits object. Note that, in particular, the quality criterion for the Maximum

Aspect Ratio mesh measure is controlled by the Edge Length Ratio setting in the Mesh Analysis> Mesh Limits object. You can double-click a red mesh measure to color the “bad” mesh elements

red in the viewer.

The Layers > Shroud Tip object is shown in red text in the object selector. In the next section, you

will modify the shroud tip layer to improve the quality.

6.6.1. Modifying the Shroud Tip Layer

1. Right-click a blank area in the viewer, and click Transformation > Blade-to-Blade (Theta-M') from the

shortcut menu.

This causes the viewer to use blade-to-blade coordinates, making it easy to see the mesh topology.

This coordinate system is angle-preserving and minimizes the effect of changing radius on viewing

and manipulation.




3. Turn off the visibility of Layers > Hub.

4. Open Layers > Shroud Tip .

5. Double-click Maximum Face Angle .

The face angles need improvement near the upstream end.

6. Hold Ctrl+Shift and drag the master control point as indicated by the displacement vector in Fig-

ure 6.2: Master Control Points Adjusted on Shroud Tip Layer (p. 49). The length of the displacement

vector is a general guide for where to position the control point. Precise positioning of the point is

unnecessary.

Note

To select and drag control points without holding down Ctrl+Shift, you can click the

Select icon, then select and drag control points with the left mouse button.

Figure 6.2: Master Control Points Adjusted on Shroud Tip Layer

6.7. Adding Intermediate Layers

ANSYS TurboGrid can add layers as required in order to capture spanwise variations in the geometry.

This process happens when you generate a mesh, but can also be initiated manually, as demonstrated

next:



Adding Intermediate Layers

1. Turn on the visibility of Layers > Hub to show the hub layer, then right-click a blank area in the

viewer, and click Transformation > Cartesian (X-Y-Z) from the shortcut menu.

2. Right-click in the viewer and click Predefined Camera > Isometric View (Y up).

By viewing the hub and shroud layers from this angle, you can see where the new layers are added.

3. Open Layers .

Note that the message indicates that 7 layers will be added.

4. Click Auto Add Layers .

ANSYS TurboGrid adds additional layers as required; in this case, 7 layers are added.

5. Turn on the visibility of a new layer to see it in the viewer.

6. To check the mesh quality on a new layer, open it, select Refined Mesh Visibility, and click Apply.

Note that the face angles are acceptable on the new layers.



mesh:







The mesh statistics shown here may differ slightly from what you see, mainly due to the freehand

movement of the control points:






As specified in the problem description, the mesh should contain an inlet domain and an outlet domain.

Add these next:

1. Open Mesh Data .

2. On the Mesh Size tab, select Inlet Domain and Outlet Domain.

3. Click Apply.

6.11. Regenerating the Mesh

After specifying that inlet and outlet domains should be added, the original mesh was deleted. Generate

the new mesh:



1. Open Mesh Analysis . Note that the Maximum Edge Length Ratio mesh measure is extremely

large. By displaying this mesh measure, you will see that some of the mesh elements that exceed the

criterion are those at the inlet where the mesh meets the rotation axis. This is expected, since the element

edges at this location have zero length. This is normal and expected wherever the hub reaches the axis

of rotation.



Analyzing the New Mesh

2. View the mesh on the inlet and outlet (not the passage inlet and outlet, but the inlet and outlet of the

entire mesh) by turning on the visibility of the corresponding 3D Mesh objects.


Save the mesh:




4. Set File name to fan.gtm .


6. Click Save.





3. Click Save.



Chapter 7: Splitter Blades






7.5. Reviewing the Topology Settings








• Review the topology type for each blade.

• Create a mesh involving splitter blades.

As you work through this tutorial, you will create a mesh for a blade set of a centrifugal compressor

that has splitter blades. A typical blade set is shown by the black outline in the figure below.



The blade row contains 7 blade sets, each containing one main blade and one splitter blade. The blade

row revolves about the negative Z-axis. The blades are flank milled and have cut-off trailing edges.

Within the blade passage, the maximum diameter of the shroud is approximately 13 cm.




1. Prepare the working directory using the files in the examples/splitter directory.





Splitter Blades


Load the BladeGen.inf file:



This geometry involves flank milled blades. For more information on flank milled geometry settings,

see Method in the TurboGrid User's Guide.


For this compressor mesh, H/J/C/L-Grid is an appropriate topology choice.



3. Set Method to H/J/C/L-Grid .



5. Leave Include O-Grid > Width Factor set to 0.5 .

This makes the O-Grid thickness equal to half the average blade thickness. In general, a suitable

value of the O-Grid thickness depends on the blade geometry, topology type, and mesh density.

Trial-and-error adjustments are sometimes required to establish a good value when creating the

first mesh for a particular blade.












To see which topology types ANSYS TurboGrid used for the upstream and downstream ends of each

of the two blade passages, do the following:

1. Open Topology Set > Main Blade and click the Advanced Parameters tab.



Reviewing the Topology Settings

Note that ANSYS TurboGrid has selected a J-Grid topology for the leading edge, and an H-Grid

topology for the trailing edge. The J-Grid is more suitable than the H-Grid for the leading edge

because of the higher blade angle.

2. Open Topology Set > Splitter Blade 1 and click the Advanced Parameters tab.

Note that ANSYS TurboGrid has selected an H-Grid topology for both ends of the splitter blade.





The Layers > Hub object is shown in red text in the object selector.

7.7.1. Modifying the Hub Layer


shortcut menu.

This causes the viewer to use blade-to-blade coordinates, making it easy to see the mesh topology.

This coordinate system is angle-preserving and minimizes the effect of changing radius on viewing

and manipulation.


3. Turn off the visibility of Layers > Shroud .

4. Open Layers > Hub.


The face angles need improvement near the upstream end.

6. Move the master control point as indicated by the displacement vector in Figure 7.1: Master Control

Point Adjusted Near Hub Leading Edge (p. 57).


Splitter Blades

Figure 7.1: Master Control Point Adjusted Near Hub Leading Edge



mesh:





The mesh statistics shown here may differ slightly from what you see, mainly due to the freehand

movement of the control points:



Analyzing the Mesh






Save the mesh:




4. Set File name to compressor_splitter.gtm .


6. Click Save.



1. Select File > Save State As.


3. Click Save.


Splitter Blades

Chapter 8: Tandem Vane










8.9. Further Modifying the Hub Layer





• Load geometry data from a CFG file.

• Copy control points and their custom positional offsets from one topology layer to another.

• Use “sticky” control points.

• Create a mesh involving tandem vanes.

As you work through this tutorial, you will create a mesh for a blade set of a radial machine component

that has tandem vanes. A typical blade set is shown by the black outline in the figure below.



The component has 16 blade sets, each containing one main blade and one tandem vane. A clearance

gap exists between each blade and the shroud. Within the blade passages, the maximum diameter of

the shroud is approximately 52.2 cm.

You will begin by loading the geometry from a CFG file. You will define the mesh topology with settings

that help to reduce mesh skew by making the mesh around each blade more independently-controlled.

Finally, you will adjust the topology and generate a fine (high-resolution) mesh.

In order to avoid long processing times, you will establish a reasonable topology before specifying a

fine mesh density.




1. Prepare the working directory using the files in the examples/tandem directory.





Tandem Vane


Load the tandem.cfg file using units of cm, then remove the shroud clearance gap from the main

blade in accordance with the problem description:

1. Select File > Load CFG.

2. In the top-right corner of the Load CFG File dialog box, set Length Units to cm.

ANSYS TurboGrid will interpret the numerical data in the CFG file using these units.

3. Open tandem.cfg from the working directory.


For this tandem vane mesh, H/J/C/L-Grid is an appropriate topology choice.











the blades, compared to the blade thickness.

6. Set One-to-one Interface Ranges > Periodic to None.

The periodic interface is the interface between blade sets.

7. Set One-to-one Interface Ranges > Passage to None.

The passage interface is the interface between the blade passages in the blade set.

The Periodic and Passage interface range settings, when set to None, allow the nodes to be

misaligned across the respective interface; the nodes on one side of an interface are not required

to connect in a one-to-one fashion with the nodes on the other side of the interface. When you

set up the resulting mesh in a CFD simulation, a General Grid Interface will be required to connect

the periodic surfaces. While such an interface may require more processing time and may be less

accurate than a one-to-one interface, the benefit of using a GGI interface is that the passage meshes

can be adjusted independently of each other. This setting is often beneficial for turbomachinery

components that have tandem vanes. You could run this tutorial with Periodic and Passage set

to Full , but the process of setting the topology distribution would be more difficult (and for some

geometries, impossible).















To see which topology types ANSYS TurboGrid used for the upstream and downstream ends of each

of the two blade passages, do the following:

1. Open Topology Set > Main Blade and click the Advanced Parameters tab.

Note that ANSYS TurboGrid has selected a J-Grid topology for both ends of the main blade.

2. Open Topology Set > Blade Blade 1 and click the Advanced Parameters tab.

Note that ANSYS TurboGrid has selected a J-Grid topology for the leading edge, and an H-Grid

topology for the trailing edge. The H-Grid is more suitable than the J-Grid for the trailing edge

because of the lower blade angle.




These settings produce a coarse mesh. Later in this tutorial, you will specify a fine mesh. By leaving the

mesh coarse for now, you will reduce processing time while adjusting the topology.


The Layers > Hub and Layers > Shroud Tip objects are shown in red text in the object selector.

In this case, the main problem is a high amount of skew in the mesh upstream of the tandem vane.

This problem will be fixed by moving and adding control points.


Identify problem areas on the hub layer and adjust the topology accordingly:



Tandem Vane

2. Right-click a blank area in the viewer, and select Predefined Camera > View From +Z from the shortcut

menu.

3. Turn off the visibility of Layers > Shroud Tip .


5. Double-click Minimum Face Angle .

Observe the areas that are marked as red. These areas have face angles that are too small.

6. Zoom in on the area shown in Figure 8.1: Moving a Control Point on the Hub Layer (p. 63).

7. Move the master control point as indicated by the displacement vector in Figure 8.1: Moving a Control

Point on the Hub Layer (p. 63).

Figure 8.1: Moving a Control Point on the Hub Layer

8. Double-click Minimum Face Angle to refresh the display of areas that still require adjustments.

9. Insert a master control point at the top of the red area, then move it as indicated by the displacement

vector in Figure 8.2: Inserting and Moving a Control Point on the Hub Layer (p. 64):

1. Right-click the location where the new control point is to be added.



Reviewing the Mesh Quality on the Hub and Shroud Layers

2. Select Control Point > Insert Master.

Figure 8.2: Inserting and Moving a Control Point on the Hub Layer

10. Double-click Minimum Face Angle and then Maximum Face Angle to see which area of the

hub requires improvement.

There is an area of high skew, shown in the left side of Figure 8.3: Inserting and Moving Another

Control Point on the Hub Layer (p. 65), that may or may not be shown in red (because the face

angles are near the limit established in the Mesh Analysis > Mesh Limits object).

11. Insert a master control point and move it as shown in Figure 8.3: Inserting and Moving Another Control

Point on the Hub Layer (p. 65).

The control point is on the interface between blades and belongs to the tandem vane blade passage.

You may need to zoom in and turn on the topology visibility (in the Layers > Hub object) to insert

the point at the desired location. The desired location of the point to be inserted is at the intersec-

tion of the topology line that you want to move and the topology line on the interface between

the adjacent passages. If you have chosen the correct location, a red line that shows the range of

influence of the new control point will stretch into the passage for the tandem vane; if the red line

stretches downward into the main blade passage, click Edit > Undo and try again.


Tandem Vane

Note that you are moving the new control point past a control point in the main passage. This is

possible because One-to-one Interface Ranges > Passage is set to None, meaning that the interface

is a GGI interface.

Figure 8.3: Inserting and Moving Another Control Point on the Hub Layer

12. Confirm that the mesh statistics have improved for the Hub layer.

Make further adjustments as necessary in order to achieve an acceptable range of face angles.

Confirm that the only elements that exceed the maximum aspect ratio are those next to the blade

surfaces.

8.7.2. Modifying the Shroud Tip Layer

Identify problem areas on the shroud tip layer and adjust the topology accordingly:


2. Turn on the visibility of Layers > Shroud Tip .

3. Click the Fit View icon.





5. Examine the mesh statistics and note any problem areas.

6. Right-click the Hub layer object in the object selector, then select Copy Control Points to Shroud.

The control point adjustments you made to the hub layer, and the newly-created control point,

are copied to the shroud tip layer. The mesh statistics improve on the shroud tip layer as a result

of this operation.


As mentioned at the beginning of this tutorial, you will increase the mesh density. Such an increase in

mesh density can result in a more accurate CFD solution.

1. Open Mesh Data .

2. On the Mesh Size tab, set Method to Target Passage Mesh Size .

3. Set Node Count to Fine (250000) .

4. Click Apply.

Note

In some cases, the mesh quality can be adversely affected by increasing the mesh density,

making further adjustments necessary.

8.9. Further Modifying the Hub Layer

As a result of changing the mesh density, the mesh quality on the hub layer has changed slightly. A

portion of the hub layer now contains elements with unacceptable face angles.

Fix the hub layer:


2. Turn on the visibility of Layers > Hub.

3. Click Fit View .


5. Examine the mesh statistics and note the area with bad face angles downstream of the main blade, as

shown in Figure 8.4: Poor Face Angles (p. 67).


Tandem Vane

Figure 8.4: Poor Face Angles

6. In preparation for the next step, make the two control points that are located slightly downstream of

the main blade “sticky” by right-clicking each one and selecting Sticky.

These two points are circled in Figure 8.5: Making Control Points “Sticky” (p. 68).



Further Modifying the Hub Layer

Figure 8.5: Making Control Points “Sticky”

7. Add two master control points further downstream on the same master topology lines, then move them

as shown in Figure 8.6: Adding and Moving Control Points (p. 69).

As you move these control points, the other control points that you previously made sticky remain

stationary because they are sticky. If they were not sticky, they would move because they are on

the line of influence of the added master control points.

Note

A sticky control point will not remain stationary if you move a pre-defined master control

point on the same master topology line.


Tandem Vane

Figure 8.6: Adding and Moving Control Points

Confirm that the mesh measures are acceptable.



mesh:



Save the mesh:




4. Set File name to tandem.gtm .




Saving the Mesh

6. Click Save.





3. Click Save.


Tandem Vane

Chapter 9: Batch Mode Studies

Note

This tutorial requires using ANSYS TurboGrid in batch mode, which is not possible from ANSYS

Workbench.

This tutorial has two parts:

• Part 1: Parametric Study (p. 71)

• Part 2: Grid Refinement (p. 75)

Part 1 of this tutorial demonstrates one basic way of performing a parametric study using ANSYS Tur-

boGrid in batch mode: using a script loop to repeatedly modify and run a session file with ANSYS Tur-

boGrid. Each modified session file loads a baseline state file, reloads the blade geometry from a different

file, and generates and saves output (including a mesh).

Part 2 of this tutorial demonstrates a grid refinement study using a method similar to part 1. The main

difference in part 2 is the use of the “end ratio” option throughout the mesh data specification to allow

the grid refinement to occur evenly through the mesh.

Variations of the algorithm described in this tutorial are possible. For example:

• You could modify the state file instead of the session file.

• You could use a loop within a session file (written in Perl) to avoid loading and closing ANSYS TurboGrid

repeatedly, which should improve efficiency.

Such variations are beyond the scope of this tutorial. You are encouraged to try the algorithm used in

this tutorial and then explore other methods as required in order to meet your specific requirements.



9.2. Part 1: Parametric Study

This part of the tutorial includes:

9.2.1. Starting ANSYS TurboGrid

9.2.2. Defining the Geometry

9.2.3. Creating the Topology and Modifying the Mesh

9.2.4. Creating the Session File

9.2.5. Running the Session File








9.2.2. Defining the Geometry

1. Select File > Load BladeGen.

2. Open the BladeGen.inf file.

3. Select File > Load Curves.

4. Set TurboGrid Curve Files > Blade to profile.1.curve .

5. Click OK to load the geometry.

6. Edit Geometry > Blade Set > Shroud Tip .



9. Click Apply.

9.2.3. Creating the Topology and Modifying the Mesh










7. Double-click Mesh Data to open it for editing. All settings will be changed to use explicit node counts.

8. Configure the following setting(s):


Batch Mode Studies

ValueOptionTab

Topology Block Edge

Split

MethodMesh

Size

Element Count and SizeSpanwise Blade Distribution Paramet-

ers > Method

Passage

Element Count and SizeO-Grid > Method

Element Count and SizeShroud Tip Distribution Para-

meters > Method

Shroud

Tip

9. Click Apply.

10. Save the state to baseline_mesh.tst .

11. Quit ANSYS TurboGrid.

You now have a state file that sets up a mesh based on profile.1.curve .

The particular blade geometry used by the state file needs only to be representative of the geometries

that will be used in the study because it will be overridden by what is specified in the session file, which

is produced next.


1. Start ANSYS TurboGrid.

2. Select Session > New Session from the menu bar to create a new session named generate_mesh.tse .

3. Start recording to the session file by clicking Start Recording .

4. Load the state file that was saved earlier (baseline_mesh.tst ).

The session is now at the point where you would typically make a change to the state. In this case,

the change will be to select a new blade curve file. To be able to load a new file, the CCL (CFX

Command Language) block responsible for loading the geometry will be included in the session

file at this point; you will create this CCL block in the next step. With that block created, you can

create a script to control which blade geometry file is loaded by changing the name of the file

within the CCL block. (The script creation is in the next section.)

5. Open Geometry > Blade Set > Blade 1 for editing and click Apply without changing any settings.


7. Select File > Save Mesh As and save the mesh with filename mesh.1.gtm with File type set to ANSYSCFX and Export Units set to cm.

8. Select Tools > Command Editor and enter the following lines in the Command Editor dialog box:

! $minFAngle = minVal("Minimum Face Angle", "/DOMAIN:Passage")*180/3.14159;! open F,"> mesh_statistics.1.txt";! print F "minimum face angle in Passage mesh: $minFAngle\n";! close F;



Part 1: Parametric Study

9. Click Process, then Close. This adds Power Syntax commands that cause Minimum Face Angle to

be written to a file.

10. Stop recording the session file by clicking Stop Recording .

11. Exit ANSYS TurboGrid.

A prompt will suggest that you save the state. You do not have to save the state since this was

done earlier.

You now have a session file that loads the baseline state file, reloads the blade geometry, creates a

mesh, saves the mesh, and generates statistical output for the mesh.


1. Using a basic text editor, write a script that, in a loop, modifies the blade file name in the session file,

and runs each modified session file using ANSYS TurboGrid in batch mode. You may give this file any

name. The example script shown here is written in Perl:

Note

This script defines and uses a variable, turbogrid , which must be defined as the full

path name to the cfxtg.exe in the bin directory of the ANSYS TurboGrid installation.

#!/usr/bin/perl# Point to the location of the cfxtg.exe (full pathname),# usually in <CFXROOT>/bin/$turbogrid = "C:/Program Files/ANSYS Inc/v145/TurboGrid/bin/cfxtg.exe";# Initialize the input and output session filenames.$base_tse = "generate_mesh.tse";$output_tse = "gen_mesh.tse";

# Get the baseline session file data.open(BASE_FH, "<$base_tse")or die "Can't open file (${base_tse}) for input: $!";@session_data = <BASE_FH>;close(BASE_FH);

# Loop over each blade geometry file.foreach $loopindex(1,2){ # Make a copy of the baseline session file # so we don't destroy the original template. @copy_data = @session_data;

# Write a session file (based on the original session file) that is # customized to use the blade associated with this loop. open(OUTPUT_FH, ">$output_tse") or die "Can't open file (${output_tse}) for output: $!"; foreach $line (@copy_data) { chomp($line); $line =~ s/\.1\./\.${loopindex}\./g; print OUTPUT_FH "$line\n"; } close(OUTPUT_FH);

# Run TurboGrid in batch mode with the customized session file. (system("\"${turbogrid}\" -batch \"${output_tse}\"") == 0) or die "Batch run of TurboGrid failed ($?): $!";}exit 0;


Batch Mode Studies

2. Run the script shown above by opening a command prompt from the ANSYS TurboGrid Launcher (with

the correct working directory set) and entering the line:

perl <scriptname>

where <scriptname> represents the name of the script file.

The script will take a few minutes to run. When it completes, it will have written two .gtm files to your

working directory, as well as two text files containing the value of the minimum face angle.

9.3. Part 2: Grid Refinement

This part of the tutorial includes:


9.3.2. Defining the Geometry and Topology








9.3.2. Defining the Geometry and Topology

1. Select File > Load BladeGen.


3. Edit Geometry > Blade Set > Shroud Tip .



6. Click Apply.










Part 2: Grid Refinement



13. Double-click Mesh Data .

14. Configure the following setting(s):

ValueOptionTab

Target Passage Mesh

Size

MethodMesh

Size

SpecifyNode Count

End RatioSpanwise Blade Distribution Paramet-

ers > Method

Passage

End RatioO-Grid > Method

Match Expansion at

Blade Tip

Shroud Tip Distribution Para-

meters > Method

Shroud

Tip

15. Click Apply.

16. Save the state to baseline_mesh.tst .


You now have a state file that sets up a mesh based on the default value of the target mesh node

count.

The particular mesh node count target used by the state file will be overridden by what is specified in

a session file, which is produced next.


1. Start ANSYS TurboGrid.

2. Create a new session named generate_mesh.tse .

3. Start recording to the session file by clicking Start Recording .

4. Load the state file that was saved earlier (baseline_mesh.tst ).

The session is now at the point where you would typically make a change to the state. In this case,

the change will be to select a different target mesh node count. To be able to change the target

mesh node count, the CCL (CFX Command Language) block responsible for specifying the mesh

data settings will be included at this point in the session file; you will do this in the next step. With

that block created, you can create a script to control the target mesh node count by changing the

Target Mesh Node Count CCL parameter in the CCL block. (The script creation is in the next

section.)

5. Double-click Mesh Data to open it and click Apply without changing any settings.



Batch Mode Studies

7. Select File > Save Mesh As and save the mesh as outputmesh.1.gtm with File type set to ANSYSCFX and Export Units set to cm.

8. Select Tools > Command Editor and enter the following lines in the Command Editor dialog box:

! $minFAngle = minVal("Minimum Face Angle", "/DOMAIN:Passage")*180/3.14159;! $nodeCount = count("/DOMAIN:Passage");! open F,"> meshstatistics.1.txt";! print F "minimum face angle in Passage mesh: $minFAngle\n";! print F "number of nodes in Passage mesh: $nodeCount\n";! close F;

9. Click Process, then Close. This adds Power Syntax commands that cause Minimum Face Angle and

the node count to be written to a file.

10. Stop recording the session file by clicking Stop Recording .


A prompt will suggest that you save the state. You do not have to save the state since this was

done earlier.

You now have a session file that loads the baseline mesh state file, reapplies the Mesh Data settings,

creates a mesh, saves the mesh, and generates statistical output for the mesh.


1. Write a script that, in a loop, modifies the target passage node count in the session file, and runs each

modified session file using ANSYS TurboGrid in batch mode. The example script shown here is written

in Perl:

Note

In the following script, the two lines following the commented line

#### The next two lines ... #### are meant to be entered as a single line.

Also, this script defines and uses a variable, turbogrid , which must be defined as the

full pathname to the cfxtg (cfxtg.exe ) file in the bin directory of the installation.

#!/usr/bin/perl# Point to the location of the cfxtg.exe (full pathname),# usually in <CFXROOT>/bin/cfxtg.exe$turbogrid = "C:/Program Files/ANSYS Inc/v145/TurboGrid/bin/cfxtg.exe";# Initialize the input and output session filenames.$base_tse = "generate_mesh.tse";$output_tse = "gen_mesh.tse";# This is a list of the target node values to be used.@target_nodes = (50000, 100000, 200000);# Get the baseline session file data.open(BASE_FH, "<$base_tse")or die "Can't open file (${base_tse}) for input: $!";@session_data = <BASE_FH>;close(BASE_FH);# Loop over each target node value.$loopindex = 1;foreach $target (@target_nodes) { # Make a copy of the baseline session file # so we don't destroy the original template. @copy_data = @session_data;



Part 2: Grid Refinement

# Write a session file (based on the original session file) that is # customized to use the target node count associated with this loop. open(OUTPUT_FH, ">$output_tse") or die "Can't open file (${output_tse}) for output: $!"; foreach $line (@copy_data) { chomp($line); $line =~ s/\.1\./\.${loopindex}\./g;#### The next two lines should be combined into one single line. #### $line =~ s/Target Mesh Node Count = [0-9][0-9]*/Target Mesh Node Count = ${target}/g; print OUTPUT_FH "$line\n"; } close(OUTPUT_FH); # Run TurboGrid in batch mode with the customized session file. (system("\"${turbogrid}\" -batch \"${output_tse}\"") == 0) or die "Batch run of TurboGrid failed ($?): $!"; # Prepare for next loop iteration. $loopindex++;}exit 0;

2. Run the script shown above by opening a command prompt from the ANSYS TurboGrid Launcher (with

the correct working directory set) and entering the line:

perl <scriptname>

where <scriptname> represents the name of the script file.

The script will take a few minutes to run. When it completes, it will have written some .gtm files to

your working directory, as well as some text files containing the value of the minimum face angle and

the number of nodes in the mesh.


Batch Mode Studies

Chapter 10: Deformed Turbine




10.3. Mesh for the Deformed Blade Group

10.4. Mesh for an Undeformed Blade

10.5. Summary

10.6. Further Exercise


• Build a blade set by loading blades separately from files and rotating them into position.

• Save, load, and rotate periodic surfaces.

• Make separate and different meshes that are designed to fit together in a CFD simulation.

As you work through this tutorial, you will create meshes for modeling an axial turbine blade row that

has a deformed blade. The technique learned here can be extended to model a blade row with several

deformed blades. A blade can become deformed after being damaged, for example by the passage of

a foreign object.



The blade row contains 71 blades, one of which is deformed. The blade row revolves about the Z-axis.

A clearance gap exists between the blades and the shroud, with a width of 0.05 cm. Within the blade

passage, the maximum diameter of the shroud is approximately 56 cm.

In this case, the full 360° geometry needs to be modeled. You will accomplish this by producing a pair

of complementary meshes: one mesh for a blade group consisting of a deformed blade between two

undeformed blades, and one mesh for a single undeformed blade. By using 68 instances of the mesh

for the undeformed blade, the entire blade row can be modeled.

For compatibility between the two meshes, the mesh density should be comparable. In this case, choose

a mesh density of about 250000 nodes per blade. You will also have to ensure that the interface between

the meshes has the same shape.

Let each mesh contain an inlet domain and an outlet domain.




1. Prepare the working directory using the files in the examples/deformed directory.


Deformed Turbine




10.3. Mesh for the Deformed Blade Group

In this part of the tutorial you will create a mesh for one deformed turbine blade surrounded by one

undeformed blade on each side.

10.3.1. Defining the Geometry for the Deformed Blade Group

10.3.1.1. Loading an Undeformed Blade

You will use the provided BladeGen.inf file to load the geometry for an undeformed turbine blade.



A blade passage for an undeformed blade appears in the viewer.

10.3.1.2. Moving the Periodic Surfaces

The BladeGen.inf file specifies a machine with 71 blade sets, each containing one blade. The blades

are therefore spaced at (360/71)° intervals around the machine axis.

In the next section, you will insert two blades into the blade set to form a group of three blades. Spe-

cifically, you will insert a deformed blade, then an undeformed blade, both on the same side of the

existing undeformed blade. The result will be a group of blades with one deformed blade between two

undeformed blades.

Before inserting the blades, make room for them by widening the angular separation between the

periodic surfaces from (360/71)° to (3*360/71)°:

1. Open Geometry > Machine Data .

2. Change Pitch Angle > Method to Specified Angle .

3. Set Pitch Angle > Angle to 15.21127 degrees.

4. Click Apply.

The periodic surfaces are now (3*360/71)° apart.

10.3.1.3. Inserting Two More Blades

Insert two blades into the blade set so that there is one deformed blade surrounded by two undeformed

blades:

1. Insert a blade named Deformed Blade :

1. Right-click Geometry > Blade Set and click Insert > Blade.



Mesh for the Deformed Blade Group

2. Set Name to Deformed Blade and click OK.

The tree view displays Deformed Blade in a bold, italic, blue font (white when selected). This

indicates that the object requires more information. In particular, the file name reference and/or

the position of the blade must be changed so that the new blade is different from the original

blade.

2. Enter the following settings for Deformed Blade :

ValueSettingTab

de-

formed.curve

File NameBlade

(Selected)Axial RotationTrans-

form 5.070423

[degree]

Axial Rotation >

Angle

3. Click Apply.

The tree view now displays Deformed Blade in plain black text. This indicates that the object

now has all the required information.

4. Insert a blade named Blade 3 .

5. Enter the following settings for Blade 3 :

ValueSettingTab

profile.curveFile NameBlade

(Selected)Axial RotationTrans-

form 10.140845

[degree]

Axial Rotation >

Angle

6. Click Apply.

You now have a blade set with three blades, as shown in Figure 10.1: Blade Set Containing a Deformed

Blade (p. 83).


Deformed Turbine

Figure 10.1: Blade Set Containing a Deformed Blade

10.3.1.4. Adding a Shroud Tip

As stated in the problem description, the blade set requires a blade tip clearance of 0.05 cm at the

shroud. Add this clearance by editing the Shroud Tip object:


2. Enter the following settings for Shroud Tip :

ValueSettingTab

Normal

Distance

Clearance Type > Tip

Option

Shroud

Tip

0.05 [cm]Clearance Type > Dis-

tance

3. Click Apply.

ANSYS TurboGrid requires, and uses, the same shroud tip clearance for all blades in the blade set. The

shroud tips of all blades in the blade set lie on the same surface of revolution when revolved about the

axis of rotation.

10.3.1.5. Adjusting the Inlet and Outlet Points

The inlet and outlet points need to be moved. To see why, change to a meridional transform:

• Right-click a blank area in the viewer, and click Transformation > Meridional (A-R) from the shortcut

menu.

With the inlet points in their initial positions, the inlet domain (the portion of the mesh upstream of

the inlet points) is much larger at the shroud than at the hub, as measured in the axial direction. To




reduce this variation, move the inlet points closer to the blade as shown in Figure 10.2: Adjusting the

Inlet Points (p. 85), using the following procedure:


2. Enter the following settings for Low Hub Point :

ValueSettingTab

Low Hub

Pointa

CurveIn-

let

Set ACurve >

Method

0.045Curve >

Location

aThe word “Low” in “Low Hub Point” refers to the side of the passage in terms of the Theta coordinate. The “Low Hub Point”

inlet point is at the intersection of the hub and the inlet curve on the low-Theta side of the passage. Note that the Theta co-

ordinate cannot be seen in the Meridional (A-R) transform.

3. Click Apply.

4. Enter the following settings for Low Shroud Point :

ValueSettingTab

Low

Shroud

Point

CurveIn-

let

Set ACurve >

Method

0. 055Curve >

Location

5. Click Apply.


Deformed Turbine

Figure 10.2: Adjusting the Inlet Points

For consistency, move the outlet points closer to the blade as shown in Figure 10.3: Adjusting the Outlet

Points (p. 86), using the following procedure:


2. Enter the following settings for Low Hub Point :

ValueSettingTab

Low

Hub

Point

CurveOut-

let

Set ACurve >

Method

0.099Curve >

Location

3. Click Apply.

4. Enter the following settings for Low Shroud Point :




ValueSettingTab

Low

Shroud

Point

CurveOut-

let

Set ACurve >

Method

0. 089Curve >

Location

5. Click Apply.

Figure 10.3: Adjusting the Outlet Points

10.3.1.6. Saving the Periodic/Interface Surfaces

Save the periodic and interface surfaces to files for later use:

1. Click File > Save > Periodic/Interface Surfaces.

The Save Interfaces dialog box appears.

2. Ensure that Look in is set to the working directory.

3. Leave Directory empty.


Deformed Turbine

To save the surface files to a different directory, you could enter that directory name under Directory,

or else you could browse to that directory so that it appears under Look in.

4. Leave Base Filename empty.

To give the surface file names a common prefix, you could enter a prefix under Base Filename.

5. Click Choose.

Four files are saved to the working directory:

DescriptionFile Name

Low-Theta periodic surfaceBlade_1_LP.crv

Interface between Blade 1 and DeformedBlade

Blade_1_Deformed_Blade_inter-

face.crv

Interface between Deformed Blade and

Blade 3Deformed_Blade_Blade_3_inter-

face.crv

High-Theta periodic surfaceBlade_3_HP.crv

10.3.1.7. Saving the Inlet and Outlet Locations

Save the inlet and outlet locations for later use:

1. Click File > Save > Inlet.

The Save Inlet dialog box appears.

2. Set File name to inlet and click Save.

The inlet points are written to a file named inlet.crv .

3. Click File > Save > Outlet.

4. Set File name to outlet and click Save.

The outlet points are written to a file named outlet.crv .

10.3.2. Defining the Topology for the Deformed Blade Group

Apply an H/J/C/L-Grid topology to force ANSYS TurboGrid to set the specific topology type automatically

for the upstream and downstream halves of each blade:














the blades, compared to the blade thickness, at the hub.

6. Leave the One-to-one Interface Ranges settings set to Full .

These settings force the periodic interface and the passage interfaces to use one-to-one node

connections. The alternative is to use a GGI (General Grid Interface) connection, or a combination

of GGI and one-to-one connections. GGI connections allow more freedom when adjusting a mesh,

but can potentially reduce the accuracy of CFD results.

7. Set Periodicity > Projection to Float on Curves .

This setting forces the periodic surfaces of the topology (and ultimately the mesh) to lie on the

periodic surfaces that were defined as part of the geometry. This constraint is necessary to ensure

that the mesh you are currently making will fit properly with the mesh you will make later in this

tutorial.

The default setting, Float on Surface , is not suitable in this case, since it allows the periodic

surfaces of the topology to deviate from the geometric periodic surfaces as a way of improving

mesh quality.






10.3.3. Reviewing the Mesh Data Settings for the Deformed Blade Group

1. Open Mesh Data.



These settings produce a coarse mesh. In accordance with the problem description, you will increase

the mesh density later in this tutorial. Leaving the mesh density coarse in the meantime will reduce

processing time while you adjust the topology.



boxes later in this tutorial. Omitting the inlet and outlet domains in the meantime will reduce the pro-

cessing time while you adjust the topology.


Deformed Turbine

10.3.4. Reviewing the Mesh Quality on the Hub and Shroud Tip Layers of the

Deformed Blade Group

The Layers > Hub and Layers > Shroud Tip objects are colored red in the tree view, indicating

that there are problems with mesh quality that should be resolved.

10.3.4.1. Modifying the Hub Layer

View the Hub layer:

1. Right-click a blank area in the viewer, and select Transformation > Blade-to-Blade (Theta-M') from

the shortcut menu.



4. Click Fit View .

View the problem areas of the Hub layer:


The object editor shows mesh measures, such as Minimum Face Angle , for all 2D elements in

the surface mesh on the layer.


The problem areas of the mesh are colored red in the viewer.



Improve the topology distribution on the Hub layer:

• Move master control points as shown in Figure 10.4: Hub Layer Changes (p. 90).

After each change, you can update the display of problem areas in the mesh by double-clicking

Minimum Face Angle and Maximum Face Angle .




Figure 10.4: Hub Layer Changes

10.3.4.2. Modifying the Shroud Tip Layer

View the Shroud Tip layer:


2. Turn on the visibility of Layers > Shroud Tip .

3. Click Fit View .

View the problem areas of the Shroud Tip layer:






Improve the topology distribution on the Shroud Tip layer:


Deformed Turbine

1. Move master control points as shown in Figure 10.5: Shroud Tip Layer Changes - Control Point Move-

ments (p. 91).

Figure 10.5: Shroud Tip Layer Changes - Control Point Movements

2. Add a master control point at the location shown in Figure 10.6: Shroud Tip Layer Changes - New Control

Point (p. 92):






Figure 10.6: Shroud Tip Layer Changes - New Control Point

3. Restrict the freedom of movement of the added control point to movement along the O-Grid curve:

1. Open Layers .

2. On the Advanced Parameters tab, set Leading And Trailing Edge O-Grid Control Points >

Method to Curve .

3. Click Apply.

4. Move the control point as indicated in Figure 10.6: Shroud Tip Layer Changes - New Control Point (p. 92).


Deformed Turbine

If the movement of the control point were much larger, the mesh density in front of the blade

would need to be increased. In such a situation, you could use an edge split control to locally in-

crease the mesh density.

5. Improve mesh orthogonality near the deformed blade by adding and moving a master control point,

and moving another control point, as shown in Figure 10.7: Shroud Tip Layer Changes - A Second New

Control Point (p. 93).

Figure 10.7: Shroud Tip Layer Changes - A Second New Control Point

10.3.5. Increasing the Mesh Density for the Deformed Blade Group

As stated in the problem description, the mesh requires a density of about 250000 nodes per blade.

Increase the mesh density. Also add inlet and outlet blocks as prescribed in the problem description:




1. Open Mesh Data .

2. Enter the following settings for Mesh Data :

ValueSettingTab

Target Passage

Mesh Size

MethodMesh

Size

SpecifyNode

Count

750000Target

(Selected)Inlet

Domain

(Selected)Outlet

Domain

3. Click Apply.

As a result of choosing the mesh size in the previous step, ANSYS TurboGrid has re-calculated the

number of elements along various topological paths. In order to provide higher mesh resolution near

the walls, set the size for mesh elements touching the hub, blade, shroud tip, and shroud to a “y+”

value of 1. These changes can cause the mesh density to become too sparse in some locations. In this

case, the density across the O-Grid would be too sparse if left unchanged. To compensate, increase the

number of elements across the O-Grid from 9 to 18.


ValueSettingTab

y+Near Wall Element Size Specification > MethodMesh

Size 1.0e6Reynolds No.

Element Count

and Size

Spanwise Blade Distribution Parameters > MethodPas-

sage

66Spanwise Blade Distribution Parameters > # of Elements

33Spanwise Blade Distribution Parameters > Const Element

1Spanwise Blade Distribution Parameters > Size of Elements

Next to Wall (y+) > Hub

(Selected)Apply O-Grid Parameters To All Blades

Element Count

and Size

Apply O-Grid Parameters To All Blades > Method

18Apply O-Grid Parameters To All Blades > # of Elements

1Apply O-Grid Parameters To All Blades > Size of Elements Next

to Wall (y+ ) > Blade

Element Count

and Size

Shroud Tip Distribution Parameters > MethodShroud

Tip

8Shroud Tip Distribution Parameters > # of Elements

0Shroud Tip Distribution Parameters > Const Element

1Size of Elements Next to Wall (y+) > Tip


Deformed Turbine

ValueSettingTab

1Size of Elements Next to Wall (y+) > Shroud

2. Click Apply.

At the interface between the passage and the inlet domain, spanwise node alignment is adversely affected

by the high curvature of the leading edge of the deformed blade. To improve this node alignment,

change a certain setting that affects the spanwise distribution of nodes in the passage mesh:

1. Right-click Mesh Data and click Edit in Command Editor.

2. Change Mesh Generation from false to Constant Span .

3. Click Process to apply the changes.

4. Click Close.

10.3.6. Revisiting the Mesh Quality on the Hub and Shroud Tip Layers of the

Deformed Blade Group

After changing the mesh size, it is possible for the mesh quality to change. You can quickly confirm

that the face angles are acceptable by verifying that all layers are shown in black text in the tree view.

To see the exact values of the minimum and maximum face angles, open each layer in the object editor:


2. Confirm that the mesh measures are acceptable.

It is normal for the aspect ratio of the elements next to the blade to be very high.



10.3.7. Generating the Mesh for the Deformed Blade Group


mesh:


10.3.8. Analyzing the Mesh for the Deformed Blade Group

In the process of generating the mesh, ANSYS TurboGrid automatically added new layers as required

to guide the mesh in the spanwise direction. Verify the mesh quality for the added layers by checking

that each layer is listed in black text in the tree view.

Mesh statistics for the 3D mesh elements are available now that the mesh has been created. Inspect

the mesh quality of the 3D mesh:





Opening either of these objects causes the Mesh Statistics dialog box to appear. This dialog box

shows mesh measures for all 3D elements in the mesh.


You can expect higher element volume ratios near the blade, hub, and shroud, where expansion

rates in multiple directions multiply to increase the volume ratio between elements that share a

node.

You can expect high edge length ratios near the walls because the requirement to place the first

nodes from the walls at y+ = 1 causes the elements next to the walls to be highly compressed in

one direction.

3. On the Mesh Statistics dialog box, click Close.

10.3.9. Saving the Mesh for the Deformed Blade Group

Save the mesh:




4. Set File name to DeformedSection.gtm .


6. Click Save.

10.3.10. Saving the State for the Deformed Blade Group (Optional)




3. Click Save.

10.4. Mesh for an Undeformed Blade

In this part of the tutorial you will create a mesh for one undeformed turbine blade. Multiple instances

of this mesh could be used, in conjunction with the mesh you made earlier, to simulate the entire blade

row.

10.4.1. Starting a New Case

Start a new case:

• Click File > New Case.

If you chose not to save the state for the previous mesh, a dialog box will appear asking if you want

to save the state. In this case, click Save & Proceed or Proceed as appropriate.


Deformed Turbine

10.4.2. Defining the Geometry for the Undeformed Blade

You must use the same periodic surfaces in meshes that are intended to fit together along the same

blade row. In the mesh you made earlier, the deformed blade might have affected the shape of the

periodic surface, even though the deformed blade is between undeformed blades. The only way to

guarantee that the same periodic surface is used in the present mesh is to load the periodic surface

from the previous mesh.

You must use the same inlet and outlet surfaces in meshes that are intended to fit together along the

same blade row. Since you have modified the inlet and outlet surfaces in the process of making the

previous mesh, you must load them for the present mesh. Even if you had not modified the inlet and

outlet surfaces, the deformed blade might have influenced the initial shape of the inlet and outlet sur-

faces.

Define the geometry using the periodic surfaces and inlet and outlet curves that you saved earlier:



3. Use the same file, Blade_1_LP.crv , to define both periodic surfaces, and apply a (360/71)° rotation

for the high periodic surface:

1. Open Geometry > Low Periodic .

2. Enter the following settings for Low Periodic :

ValueSettingTab

From

File

MethodData

Blade_1_LP.crvFile

Name

0 [de-

gree]

Rota-

tion

Angle

3. Click Apply.

4. Open Geometry > High Periodic .

5. Enter the following settings for High Periodic :

ValueSettingTab

From FileMethodData

Blade_1_LP.crvFile

Namea

5.070423

[degree]

Rota-

tion

Angle

aUse the same file as for the low periodic surface.



Mesh for an Undeformed Blade

6. Click Apply.

4. Load the inlet and outlet curve files inlet.crv and outlet.crv :

1. Right-click a blank area in the viewer, and click Transformation > Meridional (A-R) from the

shortcut menu so that you can better see the effect of loading the inlet and outlet curve files.


3. Click Read from File .

The Open Inlet File dialog box appears.

4. Select inlet.crv .

5. Click Open.

6. Open Geometry > Outlet and load outlet.crv in the same way.

10.4.2.1. Adding a Shroud Tip

As stated in the problem description, the blade set requires a blade tip clearance of 0.05 cm at the

shroud. Add this clearance by editing the Shroud Tip object:


2. Enter the following settings for Shroud Tip :

ValueSettingTab

Normal

Distance

Clearance Type > Tip

Option

Shroud

Tip

0.05 [cm]Clearance Type > Dis-

tance

3. Click Apply.

10.4.3. Defining the Topology for the Undeformed Blade


for the upstream and downstream halves of the blade:

1. Right-click a blank area in the viewer, and select Transformation > Blade-to-Blade (Theta-M') from

the shortcut menu.






Deformed Turbine







the blades, compared to the blade thickness, at the hub.

7. Click Apply.

Constrain the topology so that the resulting mesh has periodic surfaces that fall exactly on the geometric

periodic surfaces. This will ensure that the periodic surfaces of the present mesh will fit with those of

the mesh you created earlier for the deformed blade group.

1. Set Periodicity > Projection to Float on Curves .






10.4.4. Reviewing the Mesh Data Settings for the Undeformed Blade



These settings produce a coarse mesh. In accordance with the problem description, you will increase

the mesh density later in this tutorial. Leaving the mesh density coarse in the meantime will reduce

processing time while you adjust the topology.



boxes later in this tutorial. Omitting the inlet and outlet domains in the meantime will reduce the pro-

cessing time while you adjust the topology.

10.4.5. Reviewing the Mesh Quality on the Hub and Shroud Tip Layers of the

Undeformed Blade

The Layers > Hub object is colored red in the tree view, indicating that there are problems with mesh

quality that should be resolved.

10.4.5.1. Modifying the Hub Layer

View the Hub layer:






3. Click Fit View .








• Move master control points as shown in Figure 10.8: Hub Layer Changes (p. 100).



Figure 10.8: Hub Layer Changes

10.4.6. Increasing the Mesh Density for the Undeformed Blade

As stated in the problem description, the mesh requires a density of about 250000 nodes per blade.

Increase the mesh density. Also add inlet and outlet blocks as prescribed in the problem description:


Deformed Turbine

1. Open Mesh Data .


ValueSettingTab

Target Passage

Mesh Size

MethodMesh

Size

SpecifyNode

Count

250000Target

(Selected)Inlet

Domain

(Selected)Outlet

Domain

3. Click Apply.

To further improve similarity with the mesh for the deformed blade group, use the same “y+” values

and element counts as for that mesh:


ValueSettingTab

y+Near Wall Element Size Specification > MethodMesh

Size 1.0e6Reynolds No.

Element Count

and Size


sage


33Spanwise Blade Distribution Parameters > Const Element



Element Count

and Size

O-Grid > Method

18O-Grid > # of Elements

1O-Grid > Size of Elements Next to Wall (y+) > Blade

Element Count

and Size

Shroud Tip Distribution Parameters > MethodShroud

Tip

8Shroud Tip Distribution Parameters > # of Elements

0Shroud Tip Distribution Parameters > Const Element

1Size of Elements Next to Wall (y+) > Tip

1Size of Elements Next to Wall (y+) > Shroud

2. Click Apply.




10.4.7. Revisiting the Mesh Quality on the Hub and Shroud Tip Layers of the

Undeformed Blade

After changing the mesh size, it is possible for the mesh quality to change. You can quickly confirm

that the face angles are acceptable by verifying that all layers are shown in black text in the tree view.

To see the exact values of the minimum and maximum face angles, open each layer in the object editor:





10.4.8. Generating the Mesh for the Undeformed Blade

Create the mesh:


10.4.9. Analyzing the Mesh for the Undeformed Blade

Verify the mesh quality for the added layers by checking that each layer is listed in black text in the

tree view.





10.4.10. Saving the Mesh for the Undeformed Blade

Save the mesh:




4. Set File name to UndeformedSection.gtm .


6. Click Save.

10.4.11. Saving the State for the Undeformed Blade (Optional)



Deformed Turbine



3. Click Save.

10.5. Summary

In this tutorial, you created two meshes for modeling an axial turbine blade row with one deformed

blade. The first mesh, DeformedSection.gtm , models one deformed blade between a pair of unde-

formed blades. The second mesh, UndeformedSection.gtm , models one undeformed blade.

The complete blade row contains 71 blades. To model the complete blade row using CFX-Pre, you could

begin a new simulation using Turbo mode to define a set of 68 blades based on UndeformedSec-tion.gtm , then you could enter General mode and add DeformedSection.gtm .

This technique for modeling a single deformed blade can be extended to model multiple deformed

blades by creating a larger blade group for the deformed section.

10.6. Further Exercise

As a further exercise, you can try creating single-blade meshes for each blade in the blade group. You

can do this by creating a mesh for a single blade, using the Blade_1_Deformed_Blade_inter-face.crv and Deformed_Blade_Blade_3_interface.crv files for the periodic surfaces as

appropriate. This arrangement allows you to modify the mesh for the deformed blade without involving

other blades.



Further Exercise


Chapter 11: Francis Turbine







11.6. Specifying Mesh Data Settings






• Deal with a stepped hub.

• Use an L-Grid topology.

• Use edge split controls to increase the mesh density at specific locations.

As you work through this tutorial, you will create a mesh for a blade passage of a Francis water turbine.

A typical blade passage is shown by the black outline in the figure below.



The turbine contains 13 blades that revolve about the X-axis. Within the blade passage, the maximum

diameter of the shroud is approximately 4.23 m.

The mesh density should be set appropriately for using the SST turbulence model in a CFD simulation.




1. Prepare the working directory using the files in the examples/francis directory.





Load the geometry and view it in the meridional view:


Francis Turbine



menu.

Note the discontinuity in the hub geometry. In order to capture this discontinuity in the final mesh, the

background mesh on which it is based must also capture the discontinuity. The background mesh is

an internal mechanism that ANSYS TurboGrid uses to represent the geometry. It is based on the original

curve files and other geometry settings, and is used to generate the topology and ultimately the CFD

mesh. In general, if you have a step change or other discontinuity in the hub, shroud, or blade, you

should try increasing the resolution of the background mesh. The goal is to line up a node of the

background mesh with the point at which the discontinuity occurs. By increasing the background mesh

density, the probability increases that a background mesh node will exist within a tolerable distance of

the discontinuity. If the (CFD) mesh does not adequately follow the geometry (even with sufficiently-

high CFD mesh resolution), then increase the background mesh density further.

Increase the resolution of the background mesh:

1. Right-click Geometry > Machine Data and click Edit in Command Editor.

2. Change Turbo Transform Background Mesh Size For Topology from 2000 to 80000 .

3. Click Process to apply the changes.

4. Click Close.

11.3.1. Adjusting the Outlet Points

As can be seen in the viewer, the white diamonds that define the outlet curve are not at a uniform

distance from the trailing edge of the blade. In particular, the low hub point is much closer to the blade

than the other points of the outlet curve.

Move the outlet point on the hub farther away from the blade, and the outlet point on the shroud

closer to the blade, as follows:


2. Under List of Points, select Low Hub Point .

3. Set Method to Set R and Location to 0.50 .

4. Click Apply.

5. Under List of Points, select Low Shroud Point.

6. Set Method to Set A and Location to 1.75 .

7. Click Apply.

8. Click Generate Intermediate Points .

9. A message box warns you that the intermediate points will be deleted. Click Yes to delete the existing

intermediate points and replace them with new ones.




Looking at the intermediate point distribution in the viewer, you can see that adding more points would

significantly improve the smoothness of the curve. Add two more points to Geometry > Outlet using

one of the following procedures:

• If there are currently four intermediate points:

1. Under Curve, right-click Point 3 in the list and click New from the shortcut menu.

Alternatively, select Point 3 then, beside the list of points, click New .

2. Select the newly-added point, point 5, and set its location to (1.51 , 1.10 ) so that it is at about the

same distance from the trailing edge as the other points.

These coordinates were originally determined by moving point 5 using the mouse.

3. Click Apply.

4. Right-click Point 4 in the list and click New from the shortcut menu.

5. Set the location of the newly created point, point 6, to (1.73 , 1.73 ) and click Apply.

• If there are currently three intermediate points:

1. Under Curve, right-click Point 2 in the list and click New from the shortcut menu.

Alternatively, select Point 2 then, beside the list of points, click New .

2. Select the newly-added point, point 4, and set its location to (1.51 , 1.10 ) so that it is at about the

same distance from the trailing edge as the other points.

These coordinates were originally determined by moving point 4 using the mouse.

3. Click Apply.

4. Right-click Point 3 in the list and click New from the shortcut menu.

5. Set the location of the newly created point, point 5, to (1.73 , 1.73 ) and click Apply.

Before continuing, ensure that the outlet points are on a relatively smooth curve at a uniform distance

from the blade.



for the upstream and downstream halves of the blade:

1. Right-click a blank area in the viewer, and click Transformation > Cartesian (X-Y-Z) from the shortcut

menu.




Francis Turbine







This slight reduction in O-Grid width is needed due to the small passage width near the trailing

edge of the blade at the hub.

7. Set One-to-one Interface Ranges > Periodic to Between Blades & Upstream .

The high blade stagger angle in the downstream end of the passage makes the J-Grid and L-Grid

topologies good candidates for the downstream end of the passage. In order to make an L-Grid

topology possible in the downstream end, there must not be one-to-one node periodicity along

the periodic interface in that end of the passage.






9. Click Apply.


After a short time, the topology appears.

11. Open Topology Set > Blade 1 .

12. On the Advanced Parameters tab, confirm that H/J/C/L Topology Definition > Trailing Edge is set

to L-Grid .

13. On the same tab, confirm that Override Sharp TE Determination > Sharp Trailing Edge is selected.



The Layers > Hub and Layers > Shroud objects are shown in red text in the object selector.


The Layers > Hub object is colored red in the tree view, indicating that there are problems with mesh

quality that should be resolved.

View the Hub layer:





shortcut menu.


3. Turn off the visibility of Layers > Shroud .

4. Turn on the visibility of Layers > Hub.

5. Click Fit View .








1. Insert a master control point and move it as shown in Figure 11.1: Hub Layer Changes in Downstream

End (p. 111):



A yellow master control point should appear. If the master control point is colored magenta,

it will appear at the intersection of two red lines. In that case, delete the added point, then

right-click where one of those red lines intersected the master topology line and again select

Control Point > Insert Master.


Francis Turbine

Figure 11.1: Hub Layer Changes in Downstream End

2. Move a master control point as shown in Figure 11.2: Hub Layer Changes in Upstream End (p. 112).

The minimum face angle should now be approximately 35°.




Figure 11.2: Hub Layer Changes in Upstream End

3. For better mesh resolution along the periodic interface, use an edge split control to double the mesh

density at the lower location indicated in Figure 11.3: Increasing Mesh Density Locally (p. 113):

1. Right-click the master topology line marked “A” in Figure 11.3: Increasing Mesh Density Locally (p. 113)

and select Insert Edge Split Control from the shortcut menu.

2. In the object editor, change Split Factor to 2.0 .

3. Click Apply.

This causes more elements to be placed along the topology line marked “A” in the figure.

Note that edge split controls act on all layers.


Francis Turbine

Figure 11.3: Increasing Mesh Density Locally

4. In order to reduce the aspect ratio of mesh elements downstream of the blade, use edge split controls

to double the mesh density along the topology lines marked “B” and “C” in Figure 11.3: Increasing Mesh

Density Locally (p. 113).

11.5.2. Modifying the Shroud Layer

The Layers > Shroud object is colored red in the tree view, indicating that there are problems with

mesh quality that should be resolved.

View the Shroud layer:


2. Turn on the visibility of Layers > Shroud .

3. Click Fit View .

View the problem areas of the Shroud layer:

1. Open Layers > Shroud .








Improve the topology distribution on the Shroud layer:

• Move master control points as shown in Figure 11.4: Shroud Layer Changes (p. 114).



Moving the right-most control point will not improve the mesh immediately, but will avoid small

minimum face angles when a mesh is generated later on in the tutorial.

Figure 11.4: Shroud Layer Changes


Francis Turbine

11.6. Specifying Mesh Data Settings

In anticipation of using the SST turbulence model, increase the mesh density and set the near-wall y+

values for the hub, shroud, and blade to 1. Also add an outlet block and set its mesh type to H-Gridin Parametric Space in order to better capture the change in radius of the hub in the outlet region.

1. Open Mesh Data .

2. Enter the following settings for Mesh Data .

ValueSettingTab

Target Passage

Mesh Size

MethodMesh

Size

SpecifyNode Count

750000Target

y+Near Wall Element Size Specification > Method

(Selected)Outlet Domain

Element Count and

Size


sage


25Spanwise Blade Distribution Parameters > Const Elements




Next to Wall (y+) > Shroud

Element Count and

Size

O-Grid > Method

20O-Grid > # of Elements

1O-Grid > Size of Elements Next to Wall (y+) > Blade

H-Grid in Parametric

Space

Outlet Domain > Mesh TypeIn-

let/Out-

let (Selected)Outlet Domain > Override default # of Elements

30Outlet Domain > Override default # of Elements > # of Ele-

ments

In order to set the y+ value on the hub and shroud, you could use either the Element Countand Size method or the Boundary Layer method. In this case, the Element Count andSize option was arbitrarily chosen. As a result, the number of elements from hub to shroud, and

the number of constant-size elements in the middle section (away from the hub and shroud) were

required. The values given here were found, by trial and error, to produce a good mesh.

Similarly, to set the y+ value on the blade, you could use either the Element Count and Sizemethod or the Expansion Rate method. The Element Count and Size method was ar-

bitrarily chosen. As a result, the number of elements across the O-Grid was required. The value

given here was found, by trial and error, to produce a good mesh.



Specifying Mesh Data Settings

The number of elements in the outlet domain and in the O-Grid were changed to values that were

found, by trial and error, to produce a good mesh.

3. Click Apply.


Create the mesh:








Save the mesh:



3. Set Export Units to m.

4. Set File name to FrancisTurbine.gtm .


6. Click Save.





3. Click Save.


Francis Turbine

Index

Ccfg file, 61

Eedge split control, 105

examples, 1

Llayers

suppressing additional, 20

Ssplitter blades, 53

step change in geometry, 105

Ttutorial examples, 1




Documents

Tutorial Ansys TurboGrid