Investigations on Flow Instabilities on Airfoils by Means of Piezofoil-Arrays

Pressure sensitive piezofoil-arrays were applied in order to investigate the dynamic process of transition on airfoils in wind tunnel as well as in flight tests. First emphasis was on a dependable identification of laminar, transitional and turbulent flow regions on the basis of measured wall pressure fluctuations. Apart from this mainly practical application, more detailed analyzing methods were employed in order to examine more closely dynamic processes during transition. This includes, for example, the detection of TS-waves, investigations on the structure of turbulent spots, amplification rates of flow instabilities as well as probability density distributions of wall pressure fluctuations in transitional flows.