HIGH-SPEED CINEMATOGRAPHY OF COMPRESSIBLE MIXING LAYERS

Experiments are performed using high-speed film cinematography to temp orally resolve compressible planar mixing layer structures using shado wgraphs and planar light sheet visualization. The technique is relativ ely inexpensive and allows multiple images. The time-dependent shadowg raph and Mie scattering images are documented with a rotating mirror c amera operating at approximately 350 kHz. The results show the presenc e of large scale structures in the mixing layer which flatten as they convect downstream. Both spatial and tempora covariances have been obt ained through digital image processing which yield, on average, ellipt ical structures with convective speeds above the isentropic prediction , and non-isotropic streamwise and transverse scalar transport fluctua tions.