Computational Fluid Mechanics Studies of Conical Diffuser Flow

Abstract

Abstract Values of pressure recovery coefficient (PRC) are compared for flow through and along conical diffusers. Overall analytical, experimental and Computational Fluid Mechanics (CFM) determined characterisations are presented for a range of included angle 20, at industrially representative Reynolds numbers, and for the 7° diffuser, over a range of Reynolds numbers. The 7° diffuser is also examined for variation in PRC along its length, at one Reynolds number. All diffusers have the same diameter ratio. The results were verified against data from the internal aerodynamics literature. These examinations were carried out in order to build up confidence in the use of a proprietary CFM package as a basis for the study of flows in diffusers and, in particular, pressure distributions therein. Computation and experiments were done by undergraduate students acting in concert, on a class mini-project. Problems of modelling, boundary location and specification of numerical boundary conditions vis a vis real diffuser situations with and without inlet duct and tailpipe are described. The relationship between measured wall tappings of pressure and pressure variations and those from the numerical solution are investigated.