Afterburning Effects on Thermal Environment of Liquid Oxygen/Kerosene Rocket Under Low Altitudes

Heavy launch vehicles use liquid oxygen (LOX) and kerosene propellants for their high specific impulse and controlling precision. However, incomplete burnt exhaust gas reacts easily with air, which will influence the thermal environment. To investigate the afterburning effect on the plume flowfield at low altitudes, we established a supersonic exhaust plume model by using the three-dimensional Reynolds-averaged Navier–Stokes (RANS) methods and realizable turbulence model. Also, the nine-species and fourth-step chemical reactions are adopted to simulate the afterburning process. The validity of our numerical model is confirmed by the good agreement between calculation results and experiment data. On this basis, the thermal environment of the LOX/kerosene rocket between frozen and reaction flow at five typical altitudes are calculated and compared. The numerical results show that the secondary combustion reactions mainly occur in the mixing layer, with about an 11.9–18.6% increase in the peak temperature after considering the afterburning effects. The increase in range of the maximum temperature of the engine exhaust plume gradually reduces as the flight height increases. At the same altitude, the afterburning has more significant effect on flowfield for a larger distance from the nozzle exit. The results provide a vital foundation of analysis and calculation for the design of the LOX/kerosene rocket thermal protection.