Drag and Heat Reduction Performance for an Equal Polygon Opposing Jet

An equal polygon opposing jet can withstand huge wave drag and serious aerodynamic heating in hypersonic flow conditions. The opposing jet is able to change the flow field structure, and then it improves the aerodynamic characteristic of the hypersonic vehicle. In order to get more information about the flow field characteristics of the opposing jet, the schemes with equal polygons for the opposing jet were designed and their properties with different polygons have been investigated numerically in the paper. Also, the numerical method has been validated against the available experimental data in the open literature. The obtained results show that the drag-reduction performance is best when the number of jet angles (N) is 7, and its value reaches 26.4%. At the same time, its wall maximum heat flux is the smallest and the performance for heat protection is the best. Moreover, the maximum heat flux can be decreased by 60.6%. N has a slight influence on the position of the shock wave. When N is big enough, the difference for the flow field between the novel scheme and circle jet is very small because of the influence of the three-dimensional flow. But its practicability is not good. When N is not less than 4, the maximum heat flux sits in the datum line of the jet angle. The contour for wall heat flux owns the characteristics of the polygon. The flow control can work when N is an odd number. (C) 2016 American Society of Civil Engineers.