Investigating the rocket base flow characteristics and thermal environment of different nozzle configurations considering afterburning

During launch vehicle ascent, the base flow regimes of multi-nozzle rockets become increasingly complex owing to plume interactions. We developed a numerical method using the hybrid RANS/LES approach and the discrete ordinate method to accurately estimate the base thermal environment. Moreover, the finite-rate chemical kinetics are employed to calculate afterburning reactions. The validity of the numerical method is established by achieving a good agreement between the numerical results and wind tunnel data. Subsequently, the reacting and non-reacting flows of the three types of nozzle configurations were simulated at six different altitudes. The numerical results reveal that the plume interactions become stronger with the increase in flight height and total number of nozzles, and the maximum Cp of the four-nozzle rocket was 34.75% and 56.52% higher than that for three- and two-nozzle rocket at 40 km, respectively. After considering the afterburning effect, the maximum temperatures of the two-, three-, and four-nozzle rockets increased by 10.16%, 7.69%, and 5.43%, respectively, owing to the difference in plume collisions. With increasing altitude, the rocket base heating rate distribution changed significantly. The peak heat flux of the rocket base initially increases before decreasing with the maximum value of 147.32 kW/m2, 872.75 kW/m2, and 1395.80 kW/m2 for two-, three-, and four-nozzle rockets, respectively.