Pronounced aeroacoustic resonances are exhibited in the flowfield where a jet emerges from an orifice or a nozzle and impinges on a solid surface.One instance where such resonances are produced is in a high speed jet impingement,such as in the space launch vehicle systems,jet-engine exhaust impingement,and in the short take-off and vertical landing(STOVL) aircraft,etc.A highly unsteady flowfield leading to a drastic increase of noise level with very high dynamic pressure and thermal loads are noticed on nearby surfaces results dramatic lift loss,severe ground erosion and hot gas ingestion to the inlet in the jet engines.This highly unsteady behavior of the impinging jets is due to a feedback loop between the fluid and acoustic fields.In actual jet flow,the working gas may contain condensable gas such as steam or moist air.In these cases,the non-equilibrium condensation may occur at the region between nozzle exit and an object.The jet flow with non-equilibrium condensation may be quite different from that without condensation.Therefore,in this study,the effect of the non-equilibrium condensation of moist air on the axisymmetric under-expanded supersonic impinging jet on a vertical flat plate was investigated numerically. A a a a Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced Pronounced -engine exhaust impingement, and in the short take-off and vertical landing (STOVL) aircraft, etc. A highly unsteady flowfield leading to a drastic increase of noise level with very high dynamic pressure and thermal loads are noticed on nearby surfaces results dramatic lift loss, severe ground erosion and hot gas ingestion to the inlet in the jet engines. This highly unsteady behavior of the impinging jets is due to a feedback loop between the fluid and acoustic fields. In actual jet flow, the working gas may contain condensable gas such as steam or moist air.In these cases, the non-equilibrium condensation may occur at the region between nozzle exit and an object. jet flow with non-equilibrium condensation may be quite different from that without condensation. Herefore, in this study, the effect of the non-equilibrium condensation of moist air on the axisymmetric under-expanded supersonic impinging jet on a vertical flat plate was investigated numerically.