Combustion Heat-Release Effects on Supersonic Compressible Turbulent Boundary Layers

Influences of heat release by the hydrogen combustion in supersonic turbulent boundary layers are numerically studied using Reynolds-averaged Navier-Stokes equations. The adopted Reynolds-averaged Navier-Stokes methodology is first validated by comparing the numerical results with the existing experimental data. Studies on the effects of the flame perpendicular position inside the boundary layer reveal that, while the flame is restricted around the edge of the boundary layer, the heat release may slightly reduce rather than increase the wall heat flux because of the suppression effect on the turbulent energy transport due to heat release. However, as the flame moves toward the wall, the skin-friction reduction effect would not be obviously strengthened, but the wall heat flux could be dramatically enhanced by the increase of near-wall chemical reactions. At a given hydrogen mass flow rate, the injection scheme with a higher injection height and a lower injection velocity could be helpful to achieve a larger skin-friction reduction while maintaining a lower wall heat flux. Finally, analysis of the heat-release effects on the velocity law of the wall shows that van Driest's velocity law largely deviates from the computational results, whereas White's velocity law remains close to the numerical results within a region of approximately y+<300.