60th Annual Meeting of the APS Division of Fluid DynamicsSalt Lake City, Utah

Control and Scaling of Radius-Vectored Turbulent Boundary Layers

Using Plasma Actuators

T. Corke and R. Hewitt

Center for Flow Physics and ControlAerospace and Mechanical Engineering

University of Notre Dame

60th Annual Meeting of the APS Division of Fluid DynamicsSalt Lake City, Utah

Objectives: Investigate physics and scaling of SDBD Plasma

Actuators for flow separation control on TE radii.

Parameters: Radius, TBL thickness, free-stream speed.

Develop designs for flow separation control associated with airframe noise.

60th Annual Meeting of the APS Division of Fluid DynamicsSalt Lake City, Utah

Motivation: Airframe Noise Control

101

102

35

40

45

50

55

60

65

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80

Frequency (Hz)

Sou

nd P

ress

ure

Leve

l / F

requ

ency

(dB

/Hz)

Steady

UnsteadyPlasma OFF

x/D = 1.5

Flush-mountedmicrophone

-13.3 dB

60th Annual Meeting of the APS Division of Fluid DynamicsSalt Lake City, Utah

SDBD Plasma Actuators

Prog. Aero. Sci., 2007 (In press).

Ref: AIAA J., 42, 3, 2004

exposed electrode

dielectric

AC voltage source

covered electrode

substrate

Induced Flow

60th Annual Meeting of the APS Division of Fluid DynamicsSalt Lake City, Utah

Coanda Effect: No external flow

Plasma actuator (90 deg.)

Plasma-inducedCoanda effect

Plasma actuators

Plasma Actuators (90 & 270 deg.)

60th Annual Meeting of the APS Division of Fluid DynamicsSalt Lake City, Utah

Coanda EffectNo External Flow

60th Annual Meeting of the APS Division of Fluid DynamicsSalt Lake City, Utah

Experimental Approach:Effect of External Flow

60th Annual Meeting of the APS Division of Fluid DynamicsSalt Lake City, Utah

Experimental Setup

Flow

Light Sheet

60th Annual Meeting of the APS Division of Fluid DynamicsSalt Lake City, Utah

Results: Particle Visualization

R=10.4 cm (4.1in)U∞=6 m/s

Baseline

60th Annual Meeting of the APS Division of Fluid DynamicsSalt Lake City, Utah

Results: Particle Visualization

15.2kV

60th Annual Meeting of the APS Division of Fluid DynamicsSalt Lake City, Utah

Results: Particle Visualization

18.6kV

60th Annual Meeting of the APS Division of Fluid DynamicsSalt Lake City, Utah

Results: Particle Visualization

22.4kV

60th Annual Meeting of the APS Division of Fluid DynamicsSalt Lake City, Utah

Results: Particle Visualization

25.5kV

60th Annual Meeting of the APS Division of Fluid DynamicsSalt Lake City, Utah

Results: Particle Visualization

28.5kV

60th Annual Meeting of the APS Division of Fluid DynamicsSalt Lake City, Utah

Surface Flow Visualization Measurements of separation location was

done using surface flow visualization Mixture of evaporating oil and china clay. Applied on radius surface Oil moves according to local wall shear stress.

60th Annual Meeting of the APS Division of Fluid DynamicsSalt Lake City, Utah

Results: Separation Location

Summary:

• Min. Sensitivity to FS Velocity.

• Baseline separation location moves upstream with decreasing radius.

• Linear dependence of xs on actuator voltage

xs

Decreasing R

60th Annual Meeting of the APS Division of Fluid DynamicsSalt Lake City, Utah

Results: Flow Turning Angle

Summary:

• Min. Sensitivity to FS Velocity.

• Response of Actuator increases with decreasing radius

=xs/R

Decreasing R

60th Annual Meeting of the APS Division of Fluid DynamicsSalt Lake City, Utah

Results: Flow Turning Angle

Decreasing R

60th Annual Meeting of the APS Division of Fluid DynamicsSalt Lake City, Utah

Summary: SDBD plasma actuators effective in controlling flow separation

around a trailing-edge radius in which the approaching flow is a turbulent boundary layer.

Minimum Sensitivity to Free-stream Velocity. Baseline separation location moves upstream with decreasing radius. Linear dependence of xs on actuator voltage.

Response of Actuator increases with decreasing radius.

Minimum sensitivity to TBL thickness.

Up to 50% recovery of wake momentum in experiment.

Smaller radii more effective.