Numerical Simulation Study on Flow Field of Aerospike Rocket Engine Nozzle

This study presents a comprehensive numerical investigation of flow field characteristics in aerospike rocket engine nozzles operating under high-pressure conditions (28-35 MPa). With 3 million cells, we conducted a simulation of nominal, overexpanded, and underexpanded operating regimes for an engine with a combustion chamber pressure of 2900~3200 m/s exhaust velocity using high-order computational fluid dynamics k-ε turbulence modelling with enhanced wall treatment on a refined mesh. In the simulations, the maximum exit Mach number for the nominal mode was 3.8, and for underexpansion, 4.2 was reached, increasing the thrust coefficient by an additional ~8%. The pressure oscillation signature for higher pressures displayed distinct frequency shifts that were characteristic of lower pressure operations. The most dramatic pressure fluctuation was at the throat and the spike tip, where the internal pressure dP in the zone critically exceeded 0.25 MPa. These regions had stronger turbulent kinetic energy which was important for the heat transfer and thermal loading in these areas. The new design of the gas plug showed positive results for different ambient pressures which proved the aerospike's altitude compensating feature.