Influence of rarefied gas environment on the drag and heat reduction effect of opposing jet

In order to investigate the effectiveness of the opposing jet in rarefied gas conditions, the flow field structure and the drag and heat reduction effect of supersonic blunt body with opposing jet in rarefied gas conditions were calculated. Firstly, the pressure and heat flux with the global Knudsen number of 0.01, 0.03, and 0.05 were calculated by the direct simulation Monte Carlo (DSMC) method to analyze the drag and heat reduction effects of the opposing jet. Besides, the influence of some parameters such as the total pressure ratio, gas type, ejected flow velocity and temperature on the opposing jet in rarefied gas conditions were studied. The results show that as the global Knudsen number increases, the size of the Mach disk and the shear layer thickness increase and the area covered by the recirculation region decreases, which decrease the drag and heat reduction effect. Moreover, increasing pressure ratio can effectively improve the effect of the opposing jet. However, an excessively large pressure ratio will cause the increase in the drag coefficient and the decrease in the heat reduction efficiency. Therefore, the pressure ratio should be maintained within a proper range. Furthermore, by changing the parameters of the ejected gas, such as the gas type, jet velocity and temperature, the drag and heat reduction effect of the opposing jet in the rarefied gas condition can be improved. © 2022, Editorial Department of Journal of Southeast University. All right reserved.