Experimental investigation on interstage thermal environment of launch vehicle with multijets in wind tunnel

During the stage separation course of a launch vehicle, the environment of the stage is quite serious because of the high temperature and pressure. It is very important to investigate the pressure and heat flux distribution under the interstage thermal environment, as is good for the design of stage configuration. This paper presents the test technique of a thermal environment simulation with multi-jets of the launch vehicle stage separation in 1-meter-diameter hypersonic wind tunnel (HWT). The internal and external flows run simultaneously. A hot jet technique that makes use of five engine jets at the same time is adopted to simulate the internal flow. Pressure and heat flux measurements have also been developed. Pressure, temperature and heat flux characteristics of the first-stage fore-envelop head and the second-stage aft-envelop head which vary with different separation distances and different exhaust windows are introduced. The results indicate that the environment of a small stage separation distance is severe. The smaller separation distance is, the less is the uniformity of pressure, temperature, and heat flux distributions. A coaxial thermocouple is available to measure the heat flux between stages, whereas the accuracy of the heat flux measurement as well as the heat flux simulation rules need further exploring and studying