Dec. 12 2019 Boeing Higher Education

A study on Linear Reduced-order Model based on PIV Data of Flow Field around Airfoil

Koki NANKAI (Tohoku University, Japan)

Boeing Higher Education Program Year 2019 Performance Report

Boeing Japan, Maru-no-uchi,Tokyo

December 12, 2019 15:20 – 15:35

Dec. 12 2019 Boeing Higher Education

Flow field around airfoil

1

Flow separation (stall) Decrease in lift

Increase in drag

Angle of attack α

Lift

αFlow

Dec. 12 2019 Boeing Higher Education

Active flow control

2

Separation control using PA Lift enhancement

Drag reduction

Various control input

‒ Voltage

‒ Frequency

‒ Burst frequency (F+)

Feedback control Control input based on output

High robustness

Necessary to know state of flow fields

A model which estimates

the time advancement of

flow fields is necessary

Aono et al., AIAA J., 2017

F+ = 1

F+ = 5

Flow Field

Sensor

+−

DBD-PA

(Active Control Devices)

Observer

Dec. 12 2019 Boeing Higher Education

Objective

3

Construct the model of flow fields around an airfoil based

on experimental data

Experiment (Wind tunnel testing)

Order reduction of data

Modeling by a linear equation

Dec. 12 2019 Boeing Higher Education

Experiment

4

Wind tunnel testing

Particle image velocimetry (PIV)

Camera

Laser

Airfoil

Flow

Airfoil

t

t + dt

Experimental setup (at IFS, Tohoku university)

Dec. 12 2019 Boeing Higher Education

Modeling approach

5

Order reduction of data using POD technique

Modeling using linear equation

1st mode 2nd mode 𝑟 th mode

⋯⋯

⋯⋯

⋯⋯

⋯⋯

Reconstructed dataOriginal dataPOD

Order

reduction

zn+1 = Aznzn

A：Flow field at nth time step

：Coefficient matrix

A is calculated from experimental (PIV) data

Dec. 12 2019 Boeing Higher Education

Results

6

PIV measurements Time-averaged velocity fields

Time-resolved velocity fields

14 deg 16 deg 18 deg 20 deg 22 deg

14 deg 16 deg 18 deg 20 deg 22 deg

Dec. 12 2019 Boeing Higher Education

Results (α = 18 deg)

7

Reconstruction of fluid data using POD

PIV result Reconstructed

Dec. 12 2019 Boeing Higher Education

Results (α = 18 deg)

8

Temporal estimation by the model

Original Model

Dec. 12 2019 Boeing Higher Education

Conclusions

9

The linear reduced-order model of flow fields around the

airfoil was constructed based on experimental data

Experiment (Wind tunnel testing)

‒ Velocity fields data were acquired by PIV

Order reduction of data

‒ The order of fluid data was reduced drastically by POD

Modeling by a linear equation

‒ The model can reproduce the original data with low computational cost