Base Thermal Environment on Multinozzle Rocket Configurations

Because of lack of quantitative research on rocket base thermal environment under different configurations, three launch vehicles with different numbers of nozzle configurations are studied to analyze and establish criteria for effect of a multinozzle configuration on base heating. To simulate base convective heating during ascents, the three-dimensional compressible Navier–Stokes equations and the k − ω shear stress transport turbulence model are used to establish the reverse-flow model. Hence, the base thermal environment at different flight altitudes (nozzle pressure ratio 341 ∼ 14;425) was simulated. Results showed that peak heating occurred at lower altitude, and base thermal load was more severe with a compact rocket nozzle layout. Impinging jet caused by recovery shock affected the base flowfield through the formation of stagnation bubbles on the base plate, and led to the ring peak heating. The closure of reverse flow depends on the nozzle pressure ratio, mass flow rate of reverse flow, and effective exhaust boundary length. Consequently, a factor C was defined to assess the base convective heating generated by reverse flow in various configurations, and the standard for evaluating rocket base heating was established by introducing the factor C, which yielded results within 16% deviation from test data.