Large-Eddy Simulation of Supersonic, Turbulent Mixing Layers Downstream of a Splitter Plate

Abstract

Large-eddy simulation (LES) of spatially developing, turbulent mixing layers at convective Mach number of 0.5 are presented. The splitter plate is included inside the computational domain using high-order overset mesh method. Three inflow conditions are considered: (a) laminar, isothermal streams with velocity ratio of 0.17, (b) laminar streams with velocity ratio 0.36 and density ratio 0.64 and (c) isothermal streams with velocity ratio 0.17 and turbulent boundary layer on high speed side and laminar on slower side. For each case, the mean and turbulent intensity profiles collapse when plotted in similarity coordinates. The developement distance to achieve self-similarity in the mean velocity profile is found to be shortest for turbulent boundary layer case, followed by the isothermal laminar stream of (a) and then (b). The growth rate of the shear layer and peak self-similar values of the turbulent intensities are found to be in agreement with available experiments. For laminar exit boundary layers, sound radiation is observed in downstream direction peaked roughly at 40 degrees. The vortex pairing and breakdown to turbulence contribute significantly to the radiated sound. For turbulent exit boundary layers, the acoustic field near the shear layer is significantly weaker and trailing edge noise due to the boundary layer eddies is observed.