Pressure Recovery Performance of Straight-Channel, Single-Plane Divergence Diffusers at High Mach Numbers

Abstract

Abstract : Measurements were made of the pressure recovery of straight-channel, symmetric, single-plane divergence diffusers with inlet Mach numbers between 0.2 and 1.0. Three aspect ratios, 0.25. 1.0, and 5.0, were studied for a range of length-to-throat width ratios and divergence angles of diffuser geometries near peak recovery. Diffuser performance maps are given that show pressure recovery as a function of diffuser geometry for fixed values of throat Mach number, throat blockage, and aspect ratio for the range of variables tested. Of significant importance to the designer is the alteration in the shape of the pressure recovery contours on the performance maps with variations in Mach number, blockage, and aspect ratio. Four subprograms have measured the effect of changes in diffuser inlet Reynolds number, boundary layer shape factor, asymmetric distribution of inlet blockage around the throat periphery, and the influence of rounded throat corners on the pressure recovery behavior of the straight-channel diffuser. The importance to the designer of a knowledge of how diffuser performance depends upon the diffuser geometric and inlet parameters is discussed. The application of channel diffuser performance data to the design of centrifugal compressor diffusers is described. The channel diffuser performance measured is compared with recovery performance of the channel diffusers in centrifugal compressors.