Pressure Recovery Efficiency of Short Conical Diffusers and of Roughened Diffusers

Abstract

Two methods to delay the separation of flow in short conical diffusers are described. The 10° conical diffusers, having a suddenly enlarged outlet, have great advantages over the simple conical diffusers of same length, when the equivalent angle of divergence is greater than 20°. When the interior wall near the separation point is roughened, the loss of flow becomes lower than in the case of smooth wall because of delay of separation point. A method of analysing the effects of the separation positions and boundary layer thicknesses, on the loss of flow, is described.