ANSYS CFD for Internal and External Aerodynamics UK/staticassets/ANSYS... · ANSYS CFD for Internal and External Aerodynamics Phil Stopford Duxford Air Museum ... •Airfoil Design

© 2010 ANSYS, Inc. All rights reserved. 1 ANSYS, Inc. Proprietary© 2010 ANSYS, Inc. All rights reserved. 1 ANSYS, Inc. Proprietary

ANSYS CFD for

Internal and External

Aerodynamics

Phil Stopford

Duxford Air Museum

11th May 2011

© 2010 ANSYS, Inc. All rights reserved. 2 ANSYS, Inc. Proprietary

ANSYS, the company

• ANSYS design, develops, markets and globally supports a comprehensive range of engineering simulation software

• Proven software technologies for

– Fluid Dynamics

– Structural Mechanics

– Acoustics

– Electromagnetics

– Multiphysics• Specialized tools, incl.

– ANSYS Icepak (thermal/flow for electronics)

– ANSYS nCode DesignLife (for fatigue)

• World’s largest pool of experts providing CFD Best Practices

Emag

Acoustics

Structural

CAD

Import

Parametric

Simulation

Design

Exploratio

n

Meshing

Post-

processing

Fluid


ANSYS – addressing your current

& future CFD challenges

Transient or steady-stateLaminar and turbulent flows

Heat transfer

Buoyant flows

Incompressible / compressible

Multi-component flows, multi-phase

Real gas modeling

Filters/porous regionsReactions and combustion

Moving geometry and mesh

Rotating machinery

Solution-based adaptive remeshing

1-way and 2-way Fluid-Structure InteractionCourtesy of GE Energy

Courtesy of BMW AG


Key Enablers:• Links to almost any CAD system

• Parametric, persistent process

• Simulation focused: allows

engineers to do simulation driven

product development

• Direct modeling allows for re-

animating dumb CAD (geometry

without parameters) models

• Extensive modeling solutions

Engineering Productivity:

Geometry Modeling

Bi-directional CAD connections

Feature-Based Modeling

Direct Modeling

CAD Neutral: Direct and

Feature-Based Modeling!


Setup Wizards


Workflow

Geometry

Meshing

Problem Setup

Post Processing

Customized Menus

Increased Productivity through

Automation and Customization!


• Advanced physical models

• High-performance solvers


Accuracy & Speed

User-definedLES for highest accuracy;

RANS for all other areas

RANS

LESRe=395

New steady-state scheme as accurate as transient Wigley hull simulation

Free surface profiles

• Steady-state scheme

• Transient scheme

• Experiment

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0.0 0.5 1.0 1.5

Cavitation number

He

ad

ris

e c

oe

ffic

ien

t

Hofmann et al [20]

CFD

Recondensation simulation Cavitating flow in a centrifugal pump can also be modeled in steady state

Get reliable answers faster,

without compromise on flow physics!


6-DOF Rigid Body Solver

• Combinations of rotating mesh and

mesh morphing possible

• Implicit coupling with stagger iterations

• Example: Motion of spinning projectile

– 0.5° angle of attack

– 2,800 rad/s initial roll rate

Robust and easy-to-use motion

prediction

Courtesy of BAE Systems


Cabin Flows/Passenger Comfort

David Minns

“2-click” Demo

Pathlines within the cargo hold of the A400M Courtesy of Airbus Deutschland GmbH, IACC 2007

Growth through HPC

• Parametric

• Unsteady


0

5

10

15

20

25

30

35

40

45

50

0 2 4 6 8 10 12 14 16 18 20

Time (sec)

Halo

n C

on

ce

ntr

ati

on

(%

)

11-14-01 data

05-08-02 data

CFD-PROBE5

Fire Suppression

Probe 5CFD

Ground test

Flight test

Halon injector

Courtesy of Honeywell International, IACC 2007

Growth through HPC

• Parametric

• Unsteady


Courtesy of Nanomist Systems LLC, US

Droplet Trajectories Colored by Residence

Time

Large Water Droplet (150mm) Spatial Profiles

Efficiency of fire suppression device is critical to

minimize fire impact as soon as it is detected.

Droplet size modeling in possibly complex

geometry are simulated in order to optimize the

location and the effectiveness of fire

suppression equipment.

Temperature iso-surfaces

and droplet trajectories before

extinction, in a ship’s machinery space.

©British Crown Copyright 2007/MOD.

Published with the permission of the Controller of Her Britannic Majesty's Stationery Office

Fire Suppression


Transient Blade Row Analysis

• Additional models for transient blade row

simulations with pitch change


New TBR Model Approaches

• Additional Transient Blade

Row models

– Time Transformation

• Flow solved in tilted/inclined

“computational” time (t')

• Very fast convergence to transient

periodic solution

– Fourier Transformation

• Store solution history at phase-

shifted periodic boundaries

• Applicable to greater range of

flows than time transformation

Inclined time (t' ) is a function of the pitch

difference and rotor speed,


TBR Model Validation

• Example Validation Case

– Single-Stage Turbine showing

excellent agreement with reference

• Significantly reduced cost

– E.g. RAM savings: 4x–10x

– E.g. CPU savings: 5x–16xTime-Transformation

Reference Full DomainTemperature at a monitor point


BladeModeler Feature Summary

for Release 13.0

• Airfoil Design Mode in BladeEditor

Extending range to axial machinery

Section view with optional display

of details like LE/TE ellipse,

stagger line, airfoil centroid, etc.

Dynamical display of modified 3D sections

Profile curvature distributions and

blade sweep manipulations


BladeModeler Feature Summary

for Release 13.0

• Auxiliary View

– Blade-to-blade plots

– Blade lean graph

– Curvature view

Additional means of

reviewing designs

• Blade Parameterization

– Sweep through design

variations

– Design of experiments, …


TurboGrid Feature Summary for

Release 13.0

• ANSYS TurboGrid

– Automatic Topology and

Mesh (ATM) method

• Highest quality meshes

• Maximum automation

• Available for single blades

with and without cut-off

leading and trailing edges

Increased productivity

together with top quality

meshes and results


Integrated Design Exploration &

Optimization

Tradeoff Chart

Parametric CAD model

Response Surface and Sensitivity Chart

Section

Length

Guide

Curve

Angle

Guide

Curve

Radius

Eff

ecti

ve

Flo

w A

rea

Section Length

DOE generated with Design Points

Guide Curve

Angle

(Deg)

Guide Curve

Radius

(mm)

Section

Length

(mm)

EFA

(mm2)

Baseline 63 41 51 1100.2

Optimized 50 30 60.5 1180.4

Baseline Design Optimized Design

Gain deep insights necessary to

optimize product performance, and

produce better products faster!


Drag sensitivity

Downforce sensitivity

Total pressure drop sensitivity

Total pressure drop sensitivity

Estimated downforce improvement = 41.6N

Actual downforce improvement = 39.1N

Adjoint flow solver:• An understanding of the shape sensitivities with respect to design

variables in a single computation!

• A quantitative performance estimate due to a design change without the

need to simulate the actual change!

Adjoint is a very efficient means of

quickly exploring a design space with

thousands degrees of design freedom!

Shape Sensitivities wrt Design

Variables


• Design objective:– Maximize amplification ratio for a given size and power consumption

– 3 main design parameters, i.e. gap in annular ring, internal profile of ring, profile of external ramp

• Customer benefits include:– Explored 10-fold of design variations than would otherwise have been

possible (each day 10 instead of 1)

– Improved performance 250% over original design

Customer Example: Dyson Air

Multiplier™

Fan

Courtesy of Dyson


Fluid Flow

Thermal Stress

Fluid-Structure Interaction

Rigid Body FSI 1-way FSI 2-way FSI

Deformation

Co

urt

esy

of

Em

bra

co

Comprehensive suite of FSI

capabilities for accurate prediction of

a broad range of design scenarios


• Design objective:– To optimize the dual-outlet exhaust manifold for robust performance

– 4 main design parameters, i.e. outlet diameter of the manifold, thickness at inlet, external temperature, engine RPM

• Design constraint: – Maximum displacement should not exceed 1.5 mm!

Customer Example: Exhaust

Manifold

Fluid Flow

Deformation

Von Mises Stress

Temperature


• Design objective:– To optimize the dual-outlet exhaust manifold for robust

performance

– 4 main design parameters, i.e. outlet diameter of the manifold, thickness at inlet, external temperature, engine RPM

• Design constraint: – Maximum displacement should not exceed 1.5 mm!

Customer Example: Exhaust

Manifold

Fluid Flow

Deformation

Von Mises Stress

Temperature

All samples report maximum deformation

below 1.5 mm

Effect of engine speed and thickness at outlet on

maximum deformation


Evolution of Turbulence Models

• URANS– URANS gives unphysical single mode unsteady

behaviour

• LES (Large Eddy Simulation)– Too expensive for most industrial flows due to high

resolution requirements in boundary layers

• DES (Detached Eddy Simulation)– First industrial-strength model for high-Re with LES-

content

– Increased complexity (grid sensitivity) due to explicit mix of two modelling concepts

• SAS (Scale-Adaptive Simulation)– Extends URANS to many technical flows

– Provides “LES”-content in unsteady regions

– Von Karman length scale occurs naturally in formulation

URANS

SAS-URANS

22 /

/

yU

yULvK


Latest Development

• Zonal LES

– User-defined region where LES model is

applied

– Available for any omega-based RANS

model

• Turbulence forcing model

– Random harmonic velocity fluctuations

and turbulence K.E. suppressed

upstream of LES zone

• Near-wall modification: wall

modelled LES (WMLES)

– Uses RANS to model viscous sub-layer

– Mesh independent of Reynolds number

A mixing layer with resolved turbulence using

SAS initiated by the forcing model

Large turbulence K.E. in inner part of log layer


Courtesy of Oktal-SE

External Flow Examples

Lift and drag

AIAA DPW IV

Unsteady aerodynamics

Installation aero

High-lift aero and fluid structure interaction

• Aero efficiency

• Thermal loads

• Unsteady Loads

• Installation Effects

• Max lift

Geometry and grid courtesy of EADS

Deutschland GmbH, Military Air Systems.

NASA/Courtesy of nasaimages.org


External Flows Examples

Airframe aerodynamics

with virtual blade model

Droplet

collection

efficiencies

Mesh morpher

Can differentiate

solutions with

adaptive architecture

Ice build-up

Maliska, et al,

IACC 2007


Internal Flow Example

• Passenger comfort in

aircraft

Pathlines within the cargo hold of the A400M Courtesy of Airbus Deutschland GmbH, IACC 2007


Production and Propagation of Noise

Noise produced by transonic

propellerDomenico Caridi

Jet screechKonstantine Kourbatski, AIAA 2010-272


Validation for Cavity Flow

• Transient pressure measured @ 10 floor locations

(K20-K29)

• Power Spectrum Density (PSD) obtained from:

– Data

– Simulations

• Rossiter modes

K29


Predictions for Cavity Flow

0 200 400 600 800 1000 1200 1400

Frequency [Hz]

1E-2

1E-1

1E+0

1E+1

1E+2

1E+3

1E+4

1E+5

1E+6

1E+7

1E+8

PS

D [

Pa^

2/H

z]

Experiment

SAS Model

Pressure amplitude Power Spectrum Density

0E+0 1E-1 2E-1 3E-1 4E-1

Time [s]

-30

-25

-20

-15

-10

-5

0

5

10

15

20

25

30

Pre

ssu

re a

mp

litu

de

[K

Pa]

Experiment

SAS Model

K29


Side Mirror Flow Prediction

VorticityTurbulence structures

• Transient SST-SAS model

• EU project DESIDER Testcase

• Cylinder Diameter : D = 0.2 m

• Free stream Velocity: 140 km/h

• ReD: 520 000


Side Mirror SPL Prediction

1E+0 1E+1 1E+2 1E+3 1E+4Frequency [Hz]

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

SP

L [

dB

]Freestream Velocity = 140 km/h

Experimental data

SAS model

Sensor 112


Side Mirror SPL Prediction

1E+0 1E+1 1E+2 1E+3 1E+4Frequency [Hz]

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

SP

L [

dB

]Freestream Velocity = 140 km/h

Experimental data

SAS model

Sensor 119


Combustion Model Developments

• Real Gas Model– Peng-Robinson, Redlich-Kwong and

Soave-Redlich-Kwong EOS

– Extended to trans-critical and sub-

critical regimes

• Faster detailed chemistry

• Pollutants on frozen fields

• Arrhenius inter-phase

reactions

• Characteristic time model

• Thickened flame model

• G-equation model

0

500

1000

1500

2000

2500

3000

3500

4000

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40

Tem

p (

K)

Axial distance from injector exit (m)

- Cheng et. al.

- Fluent 13

• Expt.

Results for a trans-critical real gas case

Case A B C D E

Overall speed-up 3.7 5.5 6.5 6.2 4.4

Chemistry speed-up 6.5 42.2 116.3 69.0 11.6

Chemistry

agglomeration:

unsteady, axi-

symmetric, partially

premixed IC engine


G Scalar Combustion Model

G-equation model overview

Premixed or partially premixed

combustion (BVM)

• Level Set concept

G=f(x,t), G=G0 Interface

• G-scalar:

– signed distance from mean

flame front G=G0

• G-variance:

– turbulent fluctuation of

mean flame front flame

brush thickness lf,t

• Reaction progress )~

,~

( 2GGfc

Fresh

Mixture

G<G0

Burnt

Gases

G>G0

Flame

G=G0

G(x)

x

c(x)

G

Gl tf ~

~ 2

,

G0


Double Skin Impingement

Cooled CombustorMain Burner

Pilot Burner

PreChamber

Radial Swirler

DLE burner and combustor

technology

Courtesy of Siemens Industrial Turbomachinery Ltd.


Transient CFD analysis

without casing

Case 1:

9M tet/prism elements

with casing

Case 2:

16M tet/prism elements


Transient Combusting Simulation

PressureTemperature

• Case 2: Aerodynamic and combustion instability in

can induces pressure fluctuations in casing


Effect of including casing

Casing influence

Without casing With casing


Comparison with engine test data

Good agreement with the

experimental data.

Major shift in frequency

assumed to be due to

simplifications

Wide frequency peak in

CFD is due to limited

number of running cycles

Ref. G Bulat et al, Paper GT2009-59721, Proc. ASME TURBO Expo 2009: Power for Land,

Sea and Air, June 8-12, 2009, Orlando, FL.


7th Framework Programme of European

Community

Marie Curie Initial Training Network -

LIMOUSINE:

Limit cycles of thermo-acoustic oscillations in

gas turbine combustors

Coupling of CFD and University of Twente (Enschede, NL)

– Project coordinator, Dr Jim Kok

Keele University (Staffordshire, UK)

Imperial College (London, UK)

CERFACS (Toulouse, France)

Brno University of Technology (CZ)

University of Zaragoza (Spain)

Deutsches Zentrum für Luft- und Raumfahrt (Stuttgart,

Germany)

Ingenieurbüro für Thermo-Akustik (Munich, Germany)

Siemens Power Generation (Mülheim, Germany)

ANSYS (Abingdon, UK)Electrabel/Laborelec (Brussels, Belgium)

• Duration: 4 years from 1st

Oct 2008

• 3 experienced researchers

(post doc) and 17 early-

stage researchers


CFD-Post Developments

• Volume Rendering

– Variable visualisation through entire domain

– Transparency as function of local value

Smoke visualization for assessment

of visibility in a fire scenarioRendering of turbulent flow structures

in the wake of a bluff body


CFD-Post Developments

• Stereo viewer support

– Requirements:

• Stereo-capable

graphics card

– Includes many new

graphics cards

• Compatible stereo

display system

– Various technologies

available

– Also works for CFX-Pre

and TurboGrid


Summary

• ANSYS Fluid Dynamics offers:

– Shorter Overall Time to a Reliable Solution

• Workflow improvements, solver efficiency, …

– Increased Overall Coverage of Evolving CFD Needs

• New & improved physical models, additional code coupling, …

– Optimization through Robust Design

• Solution optimization, adjoint solver, design exploration

enhancements, …

– Customization & Automation Capabilities

• Parameterization, model access, usability, I/O, …

– Turbomachinery Extensions and Improvements

• Transient Blade Row models, geometry, meshing, …

© 2010 ANSYS, Inc. All rights reserved. 45 ANSYS, Inc. Proprietary© 2010 ANSYS, Inc. All rights reserved. 45 ANSYS, Inc. Proprietary

THANK YOU!

Documents

ANSYS CFD for Internal and External Aerodynamics UK/staticassets/ANSYS... · ANSYS CFD for Internal and External Aerodynamics Phil Stopford Duxford Air Museum ... •Airfoil Design