Effect of jet array and temperature on the flow structures of a transverse jet in supersonic crossflow

Active flow control has a wide range of applications in supersonic/hypersonic missiles, in which transverse jets have demonstrated an excellent performance in the fast response to flow. To address the problem of transverse jets in hypersonic missiles, this study carries out numerical simulations on the effects of the jet array and jet temperature on the flow structures. Firstly, the typical flow structures of a transverse jet are analyzed. The strong interaction between the under-expansion jet and the incoming flow forms a horseshoe recirculation zone in front of the jet, and the fluid passing through the barrel shock and the Mach disk together with the incoming flow forms a counter-rotating vortex pair that can interfere with the downstream shock. As the jet temperature increases, the area of the high-pressure zone increases, and the counter-rotating vortex pair induced by the jet causes stronger interference to the downstream shock, resulting in an enhancement effect on the pitching moment. An array of jets can obviously enhance the pitching moment, but when the jet temperature is high, the bow shock in front of the transverse jet will converge towards the lower surface along the circumference of the missile from both sides. This phenomenon makes the enhancement of the pitching moment weakened, therefore a reasonable jet spacing and temperature should be selected when arranging an array of transverse jets.