Numerical Study on the Effect of Supersonic Film Cooling on Dual Bell Nozzle

摘要

Flow behaviour and cooling effectiveness in a dual-bell nozzle with supersonic injection of gas film is investigated with numerical simulation in the present study.The gaseous nitrogen is injected near the inflection point to cool the extension nozzle wall.Effect of film injection on flow transition during the ascent of flight is also studied.Different coolant temperature and mass flow rate are taken to observe the change in cooling effectiveness.It is observed that the mixing layer increases with increasing coolant mass flow rate.The wall temperature along the extension nozzle is reduced drastically to around 700 K to 900 K.Transition pressure ratio is increased with injection of the film.Low temperature of the coolant gives better cooling effectiveness compared to various mass flow rates.Mach number of the injection has impact on effectiveness but not on mixing length.Effectiveness found to be better in case of low Mach number.Whereas higher mass flow rate give better mixing characteristics, but negative influence on film cooling effectiveness.