Study Of The Flow In A Ventral S-shaped Inlet Under Ground Running And At High Incidence And Low Speed

Experiments of the flow in a ventral S-shaped inlet were carried out and described in this thesis, in which the inlet was tested under ground running and at high incidence and low speed respectively. Also, in order to explore the characteristics of the flow within the inlet, a numerical study was performed and compared with the experimental data. The results show that:1. Under ground running, when the Mach number Mae of the flow at the exit increases, the total pressure recovery decrease, and the circular steady total pressure distortion, turbulence intensity and synthesis distortion increase. When Mae =0.45, the total pressure recovery coefficient equals 0.842, circular steady total pressure distortion coefficient equals 0.467%, turbulence intensity equals 1.554% and synthesis distortion coefficient equals 2.021%, which indicates that the inlet is fit enough to the engine under ground running. At high incidence and low speed, the general aerodynamic performance is similar to that under ground running. When Mae =0.45, the total pressure recovery coefficient equals 0.881, circular steady total pressure distortion coefficient equals 1.292%, turbulence intensity equals 1.513%, and synthesis distortion coefficient equals 2.805%, which meet the requirement of the matching of engine and inlet.2. The dynamic results show that: under ground running, the dynamic total pressure signals have analogy to the white noise, which indicates that there is no separations vortex flow in the inlet; at high incidence and low speed, the peek value of the power spectrum of the dynamic total pressure signals is mainly fastened on 220Hz, which must be considered for the design of the engine. And it is conformed that the flow separations occur within the duct.3. In contrast with the experiment results, the reliabilities of the CFD are verified. The numerical results show that open separations occur near the inside wall of the cowl, which may result in that the total pressure recovery and distortion are both lower.