ON THE VISCOUS VERSUS NON-VISCOUS FLOW ANALYSIS IN SUPERSONIC SPIKED INTAKES

The supersonic flow approaching the intake of a supersonic aero engine must be brought to subsonic state before reaching the compressor face stage. The velocity reduction is combined with reduction in the total pressure of the flow, which is not preferable by the designer of the supersonic gas turbine. However, the supersonic-to-subsonic change can be achieved shock wave system created by a spike just before the inlet of the intake. In the present paper, analytical and numerical techniques are coupled to analyze the flow field in 2-D, compressible, supersonic spiked intake. The analyses are carried out twice at Mach number between 1.8 to 2.2, and spike angles of 6o and 10o. Firstly, the analysis is carried out assuming non viscous flow, and secondly assuming viscous flow. The results are presented and compared based on the predicted values of the total pressure recovery at the face of the compressor. The procedure is justified by comparing with previous experimental works. The total pressure recovery is slightly influenced by the viscosity up to 2.14 Mach. The pressure recovery values predicted from the non viscous assumption are higher than the corresponding values obtained from the viscous solution. The viscosity contribution becomes more significant as the spike angle is increased from 6o to 10o, where noticeable reductions in the total pressure recovery values are obtained.

Keywords: Supersonic Flow, Viscous Flow, Gas Turbine, Supersonic Intake, Numerical Analysis.