Numerical Simulation of Thermal Environment of Nine-Nozzle Heavy-Lift Launch Vehicle

To investigate the plume flowfield and thermal environment of heavy-lift launch vehicles, a numerical model for a nine-nozzle launch vehicle was established based on the three-dimensional compressible Navier–Stokes equations, the Realizable [Formula: see text] turbulence model, the DOM radiation model, and a finite-rate chemical kinetics model. The study indicates that as the rocket ascends, the compressive effect of the external environment on the exhaust plumes gradually diminishes. Multiple plumes collide to form collision zones, and following these collisions, a gas flow directed towards the rocket base gradually forms. At altitudes below 10 km, radiation heat flux dominates the bottom heat transfer. As altitude increases, convection heat flux becomes predominant, with the total bottom heat flux peaking at [Formula: see text] at 30 km. At low altitudes, the temperature difference between the frozen flow and reaction flow is more pronounced. At 20 km altitude, the peak temperature in the reaction flow plume field is 8.28% higher than that in the frozen flow. At high altitudes, the temperature difference between the frozen flow and the reaction flow is not significant. At an altitude of 40 km, the peak temperature of the reaction flow exhaust plume is 7.15% higher than that of the frozen flow.