Drag and heat reduction mechanism of the porous opposing jet for variable blunt hypersonic vehicles

The porous opposing jet strategy which is suitable for the blunt hypersonic vehicle has been proposed and investigated numerically in this study. The numerical method is validated by the wind tunnel experimental data. This work shows that the aerodynamic performance can be improved further by combining the porous opposing jet design with variable blunt methods. When the number of jet orifices (N) is odd, the area of Mach disk and the off-distance of shock wave decrease with the increase in N. When N is even, 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 odd. However, the trend is contrary when N is even. Moreover, when N is odd, the influence 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, and thus the three factors (the number, the spacing and the radius of injection orifices) have the most optimal combination for the porous opposing jet injection to have the best performance for the drag reduction and thermal protection.