Investigation of active control of swept shock wave/turbulent boundary-layer interactions – PSP results

2004 ◽  
Vol 108 (1087) ◽  
pp. 483-490 ◽  
Author(s):  
J. S. Couldrick ◽  
S. L. Gai ◽  
J. F. Milthorpe ◽  
K. Shankar
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Active Control ◽  
Wave Drag ◽  
Pressure Sensitive Paint ◽  
Pressure Data ◽  
Pressure Sensitive ◽  
Boundary Layer Interaction ◽  
Inert Substrate ◽  
Wave Boundary

AbstractAn investigation of active control of the swept shock wave/boundary-layer interaction using ‘smart’ flap actuators is presented. The actuators are manufactured by bonding piezoelectric material to an inert substrate to control the bLeed/suction rate through a plenum chamber. The cavity provides communication of signals across the shock, allowing rapid thickening of the boundary layer approaching the shock. This splits the shock foot into a series of weaker shocks forming a lambda structure, thus reducing wave drag. Active control allows optimisation of the unimorph deflection, hence rate of mass transfer.In this paper, results of the interaction using pressure sensitive paint (PSP) are emphasised. It is shown that the use of PSP, in conjunction with discrete pressure data, enables the main features of the interaction to be observed when the actuators are subject to different deflections.

Active control of swept shock wave/turbulent boundary-layer interactions

2004 ◽  
Vol 108 (1080) ◽  
pp. 93-101 ◽  
Author(s):  
J. S. Couldrick ◽  
S. L. Gai ◽  
J. F. Milthorpe ◽  
K. Shankar
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Turbulent Boundary Layer ◽  
Active Control ◽  
Wave Drag ◽  
Boundary Layer Interaction ◽  
Shock Position ◽  
Inert Substrate ◽  
Lambda Shock ◽  
And Control

Abstract This paper looks at active control of the swept shock wave/turbulent boundary-layer interaction using smart flap actuators. The actuators are manufactured by bonding piezoelectric material to an inert substrate to control the bleed/suction rate through a plenum chamber. The cavity provides communication of signals across the shock, allowing rapid thickening of the boundary-layer approaching the shock, which splits into a series of weaker shocks forming a lambda shock foot, reducing wave drag. Active control allows optimum control of the interaction, as it would be capable of positioning the control region around the original shock position and control the rate of mass transfer.

scholarly journals Global Skewness and Coherence for Hypersonic Shock-Wave/Boundary-Layer Interactions with Pressure-Sensitive Paint

Aerospace ◽  
2021 ◽  
Vol 8 (5) ◽  
pp. 123
Author(s):  
Carson L. Running ◽  
Thomas J. Juliano
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Surface Pressure ◽  
Data Reduction ◽  
Pressure Sensitive Paint ◽  
Wave Boundary Layer ◽  
Pressure Sensitive ◽  
Hypersonic Shock ◽  
The Mean ◽  
Wave Boundary

The global surface pressure was measured on a 7° half-angle circular cone/flare model at a nominally zero angle of attack using pressure-sensitive paint (PSP). These experiments were conducted to illustrate fast PSP’s usefulness and effectiveness at measuring the unsteady structures inherent to hypersonic shock-wave/boundary-layer interactions (SWBLIs). Mean and fluctuating surface pressure was measured with a temperature-corrected, high-frequency-response (≈10 kHz) anodized-aluminum pressure-sensitive paint (AA-PSP) allowing for novel, global calculations of skewness and coherence. These analyses complement traditional SWBLI data-reduction methodologies by providing high-spatial-resolution measurements of the mean and fluctuating locations of the shock feet, as well as the frequency-dependent measure of the relationship between characteristic flow features. The skewness indicated the mean locations of the separation and reattachment shock feet as well as their fluctuations over the course of the test. The coherence indicated that the separation and reattachment shock feet fluctuate about their mean location at the same frequency as one another, but 180 degrees out of phase. This results in a large-scale ‘breathing motion’ of the separated region characteristic of large separation bubbles. These experimental findings validate the usefulness of AA-PSP, and associated data-reduction methodologies, to provide global physical insights of unsteady SWBLI surface behavior in the hypersonic flow regime. Similar methodologies can be incorporated in future experiments to investigate complex and novel SWBLIs.

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