1. Active Cancellation of Tollmien-Schlichting Instabilities in Compressible Flows Using Closed-Loop Control.
- Author
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Engert, Marcus, Pätzold, Andreas, Becker, Ralf, and Nitsche, Wolfgang
- Abstract
The present paper reports on active cancellation of natural Tollmien- Schlichting (TS) instabilities on an unswept wing in compressible flows. The research concentrates on closed-loop active wave control (AWC) experiments at Mach numbers ranging from 0.2 up to 0.4. These high velocities result in thin boundary layers and therefore in TS frequencies up to 10 kHz. Therefore, the resolution of the applied sensors as well as the amplitude and frequency domain of the actuators are subject to challenging requirements. Additionally, the velocity of the convective TS waves demands a powerful, optimized control algorithm working in real time. The AWC principle applied here delays TS induced transition by stabilizing the linear disturbance waves initiating the laminar-turbulent transition process. This method is based on the wave superposition principle, i.e. the superposition of artificially generated anti-disturbances and the naturally occurring TS disturbances. The energy consumption with this method is considerably lower than the stabilization achieved by manipulating the local mean velocity profile (e.g. boundary layer suction). [ABSTRACT FROM AUTHOR]
- Published
- 2008
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