Measurements in a compressible planar shear layer with a thermal gradient
Experiments on a compressible planar shear layer with a sharp thermal gradient between the mixing streams were conducted with the goal of adding to a set of benchmark computational fluid dynamics validation datasets for unheated mixing layers as well as obtaining the first temperature measurements within this kind of shear layer. The shear layer itself was a dual-stream air mixing layer with a convective Mach number of 0.541 and a stagnation temperature difference of about 200 K between the streams. A preexisting mixing layer facility was modified to provide for the addition of the heated stream while maintaining the original operational capacities of the facility. Three-component velocity fields along the central streamwise-transverse plane of the shear layer were obtained through the use of stereo-particle image velocimetry. Even with the novel stagnation temperature gradient, it was found that there were minor to negligible effects on the turbulence or mean velocity fields compared to previous similar investigations into the compressible shear layer, albeit with a higher shear layer growth rate. Temperature probe traverses throughout the shear layer were obtained at different streamwise points, as well as static pressure measurements along the entire test section side-wall. Schlieren visualizations in the form of high-speed videos as well as instantaneous images were also obtained, giving additional qualitative insight. Temperature field measurements were made via Filtered Rayleigh Scattering along the central streamwise-transverse plane, and the mean transverse profiles of those temperature fields calculated. It was found that the temperature field of the thermal mixing layer becomes fully self-similar much closer to the splitter plate in the streamwise direction than that of the velocity field. This work provides a basis for future studies to build upon and to further investigate compressible shear layers with gradients in stagnation temperature between the streams.
compressible, fluid dynamics, planar, turbulent, mixing, shear layers, velocity, temperature
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign