Effect of Spike Geometry on Drag Reduction for a Novel Combinational Spiked Blunt Body and Counter Jet Concept in Hypersonic Speeds

Abstract

Drag reduction at hypersonic speeds around blunt bodies is a significant challenge in aerodynamics. Various methods, including the use of spikes and counterflow jets, have been explored to mitigate this issue. This study focuses on the numerical analysis of counterflow jets on blunt bodies to achieve drag reduction at hypersonic speeds. Numerical simulation of hypersonic blunt body has been done in the present study. The blunt body is also associated with a sharp spike and opposing or counters flow jet. It has been tried to mitigate the aerodynamic wave drag by using the above two devices for hypersonic flow. Whole of the numerical study has been done in ANSYS Fluent using commercial codes. The research employs axisymmetric Reynolds-averaged Navier-Stokes (RANS) equations coupled with turbulence models such as k-ω (SST) and k-ε to simulate the flow field around blunt bodies with counterflow jets. Analysis has been carried out for an axisymmetric 60 ° blunt body. Here, air is injected from tip of the sharp spike. In this analysis, various jet (opposing) inlet conditions with different pressure ratios have been investigated. The studies have been done for 5 different L/D ratios namely – for 0.2, 0.5, 0.7, 1, 1.5. The unsteady, compressible, Navier-stroke equations are solved with classic SST (Shear Stress Transport) turbulent flow model for zero angle of attack at Mach number 8. Drag coefficient results show a significant reduction in heat flux and therefore such arrangement for hypersonic vehicles could increase the efficiency of thermal protection system several times. Thus, it could be conclude that it will be beneficial to use opposing jet at spike tip for achieving drag reduction.