Applicability Of A Straight Diffuser Design And Performance Prediction Method To Diffusers With Different Wall Contouring

The present paper applies a previously published semi-empirical method for calculating laminar and turbulent boundary layer for the purpose of analysis and design of rectangular, straight-wall diffusers (with arbitrary free stream pressure gradient) to estimate performances of diffusing channels with alternative wall geometries. The method has been used on diffusers with concave and convex wall contouring (in addition to straight profile) having the same air inlet speed. The calculation for concave-wall diffusers agreed reasonably well with available detailed experimental results over wide range of area ratio variation (1.2-2) for constant inlet blockage. However, when the prediction method was used to calculate likely performance of diffusers with convex wall contouring, it could only give poor estimates for low value area ratio diffusers (equal or less than 1.2), the method could not predict performance of higher area ratio diffusers.