Numerical investigaiton of counter-flow jet on a hypersonic for drag reduction

Abstract

A numerical investigation has been conducted for drag reduction of a blunt body with a counter flow jet at Mach number 6. The computational study was carried out by solving axisymmetric, explicit, Reynolds Averaged Navier-Stokes (RANS) equations. Spalart-Allmaras one equation are used for turbulence model. By releasing a jet into the air, the shock structure is changed from bow shock wave to multiple shock structure. Ultimately, the changed shock structure leads to drag reduction. The purpose of this study is to investigate the influence of the stagnation pressure, exit Mach number and gas species of the jet based on the parameters of momentum parameter ratio (MPR) of jet. The results show that the flow-field can be categorized long penetration mode (LPM) and short penetration mode (SPM) ii depending on the penetration length of jet. In LPM, the shock structure is continuously fluctuated so that the flow field is unstable. Therefore, even if the penetration length of jet is very long, the drag cannot be reduced significantly. On the other hand, at SPM, the shock structure is almost fixed and the entire flow field is stable. Therefore, even if the penetration length is short, the drag can be reduced by up to 40%. In conclusion, high pressure, high Mach number, and high molecular weight of jet is beneficial for drag reduction. Keywords : Hypersonic, counter-flow jet, drag reduction, Momentum parameter ratio (MPR) Student Number : 2015-20783