Effect of the Adiabatic Index on the Shock Reflection in Overexpanded Nozzle Flow

The start-up and shutdown phases of liquid rocket engine nozzles are characterized by the overexpansion of the flow, with internal boundary layer separation and shock formation. The overexpansion shocks are characterized by oscillations, which can produce dynamic side loads, reducing the safe life of the engine and possibly leading to the failure of the nozzle structure.