Boundary-layer structure with hydrogen combustion with different injection intensities

Results of numerical simulation of the influence of intensity of hydrogen injection through a porous surface in the case of hydrogen burning in the boundary layer are presented. Turbulent characteristics of the flow were simulated using the $k$–$\varepsilon$ turbulence model with Chien's modification for low Reynolds numbers. The diffusion model (infinitely large burning rate) was used to describe the chemical reaction process, but the difference in diffusion coefficients of different substances was taken into account. A comparison of injection with and without combustion shows that the presence of a heat-release front delays the laminar–turbulent transition and significantly deforms the profiles of density and viscosity of the gas mixture. As the injection velocity increases, the flame front is shifted from the porous surface toward the outer edge of the boundary layer. The contributions of injection itself and combustion to reduction of skin friction are analyzed.