Fluid-thermal coupled investigation on the combinational spike and opposing/lateral jet in hypersonic flows

摘要

The drag reduction and thermal protection mechanism induced by the spike and its combinations with jet strategy is investigated in the current study. A fluid-thermal coupled analysis is carried out to explore the impacts of the jet pressure ratio (PR), the length-to-diameter ratio (L/D) of the spike and the lateral jet location (D-L) on the peak pressure and peak heat flux of the blunt head. The obtained results suggest that the combined spike and multi-jet strategy is the most promising technology for the drag and heat reduction. The increases in jet pressure ratios including opposing jet ratio and lateral jet ratio are advantageous and provide the maximum reduction in the drag and heat flux. Specifically, for the cases of PRo = 0.2 and PRo = 0.6, the peak heat fluxes are decreased by about 2.25 kW/m(2) and 0.37 kW/m(2) respectively after 0.6 s', and the decrease rate becomes more slowly during the coupling process. Further, the negative thrust produced by the opposing jet plays a key role in the total drag component. For the L/D effect, the peak pressure and drag coefficient decreases when L/D increases. However, it is noteworthy that when L/D = 0.5, the peak heat flux is close to that when L/D = 2, which, is at a relatively low level of 104.83 kW/m(2). In addition, the lateral jet location has a decisive influence on the flow structure, drag coefficient and heat flux distribution, and DL = 8 mm gives the minimum drag and heat flux while the peak pressure is the maximum.