MEASUREMENTS OF COMPRESSIBLE TURBULENT-FLOW STRUCTURE IN A SUPERSONICMIXING LAYER

Multiple overheat cross-wire, parallel hot-wire, shadowgraph image pro cessing and high-frequency response pitot probe surveys were taken in a two-dimensional, adiabatic, supersonic, free mixing layer, consistin g of Mach 1.8 air (Re = 7 x 10(6)/m) injected tangentially into a Mach 4.0 freestream (Re = 67 x 10(6)/m). Mass flux turbulence intensity pr ofiles in three dimensions were acquired, and the axial component was found to be about 25% larger than the transverse and spanwise componen ts. Mean Favre-averaged velocity fluctuation data indicated that the a xial component was negative, while both the transverse and span were p ositive. Turbulent flow structure angles and length scales were measur ed in the fully developed region of the how The structure angles were found to be consistent with previous compressible boundary layer resul ts; however, the magnitude here was found to decrease across the mixin g layer Mach number fluctuation levels were also measured. The peak Ma ch number fluctuation level in this bow was about 10%.