Supersonic Diffuser for Radial and Mixed Flow Compressors

Abstract

Presentation is made for the design concepts of a novel diffuser that handles supersonic flow at the exit of radial and mixed flow compressors. The guide vanes incorporating a V shape at the inlet are shown to offer potentialities of a shock free deceleration of the supersonic flow. Optimum diffusion of a high-speed flow is considered. The results are applied to the design of two sets of guide vanes for the diffusing system. The experimental evaluation of these guide vanes confirms the original conceptual thinking, with a highest diffuser performance of 0.792 at an inlet Mach number of 1.3. Effect of the blade loading and of the subsonic inlet Mach number on the guide vanes are presented. Actual performance of the diffuser in a compressor of a gas turbine is discussed.