Numerical Investigation on an Under-Expanded Jet from a Rectangular Nozzle with Aft Deck

There are complicated flow field interferences between the jet-flow of engine nozzle and external flow of an aircraft, especially for the nozzle with aft deck, which probably cause the distortion of the alternating flow field morphology of shock and expansion waves in the state of under-expansion. Simultaneously, the interaction have significant impact on the flow capacity, thrust characteristics, jet direction of nozzle and the load of aft deck. Numerical simulations on an under-expanded jet from a rectangular nozzle with aft deck are performed to investigate the variation law of the aerodynamic characteristics and the jet direction under different installation angle of aft deck. The results indicate that fine mesh is necessary to capture a better results such as nozzle thrust coefficient, load distribution of aft deck, and a series of shock waves and expansion waves, and jet direction is changed obviously due to deflection of aft deck. The jet deflection caused by upward deflection of rear deck is stronger than that caused by downward deflection, accordingly, aerodynamic loss caused by upward deflection of rear deck have become more severe. The investigation on jet from nozzle with aft deck provide an effective approach and basis for the integrated design of nozzle and aft deck of new generation aircraft.