COMBINED PARTICLE IMAGE VELOCIMETRY AND VISUALIZATION EXPERIMENTS ON INSTABILITIES IN A FLAT-PLATE BOUNDARY-LAYER WITH ZERO PRESSURE-GRADIENT

Quantitative and visual data of artificially forced instabilities are acquired in a flat plate boundary layer in air. For the first time, particle image velocimetry (PIV) allows the instantaneous recording of a complete velocity field. With this technique, quantitative data are obtained within the boundary layer and very close to the wall. By using a light sheet technique it is possible furthermore to obtain visual data. Reproducible and constant conditions in the development of the instabilities are achieved by forcing the boundary layer with well-controlled disturbances. These disturbances are generated with an arrangement for acoustic excitation.