Development of a sensor-actuator-system for active control of boundary layer instabilities in compressible flows

This paper describes the development of an active control system for delaying laminar-turbulent transition in compressible flows. Convective boundary layer instabilities are detected during their linear amplification stage by a reference sensor and reduced downstream through destructive interference of artificial counterwaves. By means of highly sensitive surface sensors the transitional boundary layer for Mach numbers up to Ma=0.5 was investigated in detail. An actuator was developed for the generation of counterwaves with appropriate amplitude, wavelength, frequency range and phase. After integration of reference sensors, actuator and error sensors into a slim wing model, artificially generated boundary layer perturbations were attenuated as a first test.