关键词: 减阻防热, 激波针, 喷流, 非设计工况, 高超声速

Abstract: The combination of spike and opposing jet shows great advantage in drag reduction and thermal protection under design conditions. However, its performance will dramatically deteriorate under off-design conditions at an angle of attack. To solve the problem, this paper numerically investigates the strategies of the combination of spike, opposing jet and lateral jet, and further explores their drag and heat reduction performance. Firstly, the mechanism of the combined strategy is illustrated, and then the effects of the number and spacing of lateral jets on drag reduction and thermal protection are quantitatively analyzed. The results reveal that the oblique shock induced by the spike interacts with the reattachment shock in the windward side of blunt body, resulting in the greater peak pressure and heat flux than that in the stagnation point without protection. By adding lateral jets on the windward, the intensity of shock interaction can be remarkably alleviated, and thus the drag coefficient and peak heat flux are greatly reduced by 36% and 53.8% respectively. Further studies indicate that the performance of drag reduction and heat protection exhibit different trends with increasing lateral jet numbers and spacing. Specifically, the drag coefficient decreases by 6.5%, while the peak heat flux increases by 10.8% when the number of lateral jet increases from 1 to 4. Meanwhile, a reduction rate of 13.2% in drag coefficient and a growth rate of 4.9% in peak heat flux are obtained when the distance between lateral jets increases from 4 mm to 8 mm.

Key words: drag reduction and thermal protection, spike, jet, off-design regimes, hypersonic