Further Data on the Pressure Recovery Performance of Straight-Channel, Plane-Divergence Diffusers at High Subsonic Mach Numbers

Abstract

Measurements are reported of the pressure recovery of straight-channel, symmetric, single-plane-divergence diffusers with inlet Mach numbers between 0.2 and choking for an aspect ratio of 5.0. The data reported cover a range of length-to-throat width ratios L/W1 and divergence angles 2θ for diffuser geometries near peak recovery. These data complement data previously reported for AS = 0.25 and 1.0. Diffuser performance maps are given that show pressure recovery Cp as a function of diffuser geometry for fixed values of throat Mach number Mt, throat blockage B, and aspect ratio AS 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 Mt, B, and AS. Also reported are data on the effect of changes in diffuser inlet Reynolds number, 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. These data have underscored the necessity of understanding the cumulative effects of a number of secondary parameters on pressure recovery. The importance to the designer of a knowledge of how diffuser performance depends upon the diffuser geometric and inlet parameters is discussed.