Abstract: The opposing jet, an active flow control technology capable of drag and heat reduction, can be used in the design of hypersonic vehicles. The drag reduction characteristics of the opposing jet for the ball head, single cone, and double cone in typical missile shapes are numerically studied using CFD method, with the opposing jet generator fixedly connected to the missile body. The effects of the Mach number, jet pressure ratio and other parameters on the drag reduction effect of different objects are comparatively analyzed. The results show the existence of two modes of long and short penetration in the opposing jet flow field. The ball head has the best drag reduction effect with a small pressure ratio in the long penetration mode, while the single cone and the double-cone have better effects in the short penetration mode with large pressure ratios. An optimal pressure ratio exists to induce the best drag reduction effect. If the pressure ratio is too large, the drag reduction effect becomes worse such that the drag coefficient even increases instead of decreasing. The drag reduction effect of opposing jet is sensitive to control body selection. If the drag reduction characteristics of the opposing jet on the head were directly extended to the whole aircraft, the evaluation result would be too optimistic. Comprehensively considering the best drag reduction effect, the best pressure ratio, the mass flow rate, the required gas cylinder volume, and other influencing factors, we propose that the opposing jet should preferentially use sonic jet flow in engineering applications.

Key words: opposing jet, double-cone bodies, drag reduction characteristics, sonic jet, CFD