Coupled investigation on drag reduction and thermal protection mechanism induced by a novel combinational spike and multi-jet strategy in hypersonic flows

Abstract

Drag and heat reduction strategy in hypersonic vehicle design has already attracted worldwide attention. In this paper, a novel combinational spike and multi-jet strategy has been proposed for the drag and heat reduction in hypersonic flows. The flow field induced by this novel strategy has been numerically investigated by an in-house code. High-resolution upwind scheme (AUSMPW) and SST k-ω turbulence model are employed in the code. The fluid-thermal interaction is considered by using the conjugate heat transfer (CHT) approach. In addition, the thrust produced by the opposing jet is taken into account in computing the total drag. The influences of the spike length-to-diameter ratio, jet pressure ratio and lateral jet location on the flow field, drag reduction and heat properties are investigated thoroughly. The numerical results reveal that this novel strategy has better drag and heat reduction efficiency of unit mass flow rate, and the negative thrust induced by the opposing jet proved to be an important factor for the total drag. The spike length-to-diameter ratio has a great influence on the drag reduction, and the drag coefficient decreases significantly as the spike length-to-diameter ratio increases. However, the Stanton number is less affected by the spike length-to-diameter ratio variation. The jet pressure ratio, including the pressure ratios of opposing jet and lateral jet, are the key parameters for the drag reduction and thermal protection, and both the drag coefficient and the Stanton number decrease significantly as jet pressure ratio rises. For the lateral jet location effect, it influences the flow features, drag reduction and thermal protection significantly. The drag coefficient can be reduced by nearly 20% as the lateral jet location increases from 0.1 to 0.7, and the peak value of the Stanton number increases sharply by 49.36% when the lateral jet location varies from 0.9 to 0.1.