Opposing jet, as one of the most practical strategies to achieve the drag and heat reduction, is usually adopted to improve the aerodynamics and the aerothermodynamics of hypersonic vehicles. The porous jet strategy which is suitable for the blunt hypersonic vehicle has been proposed and investigated numerically in this study. The full Navier-Stokes equations and SST k-w turbulence model is used to obtain the flow field properties. The numerical method is validated by the wind tunnel experimental data. This work shows that the porous opposing jet is able to reduce the drag and the aero-heating of blunt hypersonic vehicles. The aerodynamic performance can be improved further by combining the porous jet design with variable blunt methods. When the number of jet orifices (N) is an odd number, the area of Mach disk and the off-distance of shock wave decrease with the increase in N. When N is an even number, the high temperature region will decrease with the increase in N. The drag reduction ratio increases with the increase of jet orifices when N is an odd number. However, the trend is contrary when N is even. Moreover, when N is odd, the effect of drag reduction is better than that when N is even. Considering both factors of the drag reduction and thermal protection, the porous jet design is useful in improving the overall performance of the blunt hypersonic vehicle. The porous jet has three-dimensional effect, so there exists the optimal injection scheme. The three factors (the number, the spacing and the radius of injection orifices) have a multi-objective optimal solution. It is thus then the drag reduction and the heat protection of the porous jet injection has the best performance.
Investigation on thermal protection and drag reduction by lateral jet in supersonic flows
