Tóm tắt

Since boundary layer combustion is an effective method to reduce skin friction in supersonic flow-fields, effects of the combustion on typical pressure gradient flow fields are numerically investigated using Reynolds-averaged Navier-Stokes (RANS) simulations. RANS method is validated by comparing the numerical results with the conducted experimental data. Wall heat flux of combustion case is reduced rather than increased although the flame is restricted in boundary layer, especially in adverse pressure gradient state. Compared with the results of no-injection cases, great skin-friction reduction can be obtained by boundary layer combustion, and further reduction can be achieved as pressure gradient increase. Then, the reduction mechanism is analyzed in details. Due to low viscosity gas injection and decline of velocity gradient, the skin friction level is reduced. Moreover, the component of shear stress, Reynolds stress, is decreased due to low density caused by combustion. Additionally, wall velocity laws of combustion coupled with pressure gradient are explored. The results show that the corrected White and Christoph's law is appropriate for velocity description even in sub-layer because the parameters used in the law are obtained at wall and modified by combustion heat release. The research popularizes the application of boundary layer combustion to common pressure gradient situation, and gives advice on wall function selection of turbulent boundary layer combustion.