Detailed parametric investigations on drag and heat flux reduction induced by a combinational spike and opposing jet concept in hypersonic flows

In the current study, the flow field behavior induced by a novel combinational opposing jet and spike concept has been investigated numerically. A comprehensive analysis on the selections of the turbulence model and the height of the first grid point off the wall (Delta x) has been conducted firstly. Then, this paper mainly focuses on the influences of the nozzle diameter (d(0)), the length-to-diameter ratio of the aerospike (L/D) and the jet pressure ratio (PR) on the flow field structures, the aerodynamic drag and heat properties. The results show that when d(0) is 2 mm, adding the opposing jet to the single spiked blunt body has no help in modifying the high drag and heat environment. However, the combinatorial thermal protection system has a great contribution to reduce the drag and heat when d(0) is 4 mm, with 45% and 38% drop on the wall Stanton number (St) and drag coefficient (Cd) respectively. The values of the wall heat flux, the static pressure and the drag coefficient decrease apparently when L/D increases from 1.0 to 1.5, while the drop rates of these indexes seem not so obvious when L/D rises from 1.5 to 2.0. Meanwhile, the introduction of the opposing jet creates a recirculation zone upstream the spike head, and there is a recirculation zone emerges downstream the aerodisk as well when L/D increases to 2.0. Both of the recirculation zones have alleviated the high temperature the aerodisk sustained significantly. (C) 2018 Elsevier Ltd. All rights reserved.