A Radial Diffuser Using Incompressible Flow Between Narrowly Spaced Disks

Owing to the geometric limitations of certain internal flow systems, the use of a conical or rectangular diffuser for the recovery of kinetic energy as static pressure is often impossible. This paper describes a study of swirl-free, incompressible flow in a radial diffuser consisting of two components: A radial channel in which the flow diffusion occurs and an inlet bend which joins the radial channel to the supply pipe outlet. A design for an efficient inlet bend is described and a study made of other geometrical parameters. The experiments showed that the pressure recovery decreased with increasing inlet boundary-layer thickness and decreasing Reynolds number, both for the radial diffuser and a 7-deg conical diffuser of the same area ratio. In addition, the pressure recovery of the radial diffuser was comparable to that of the 7-deg conical diffuser at the high Reynolds numbers generally encountered in internal flow systems. At high Reynolds numbers, it was also possible to predict theoretically the pressure recovery for the radial diffuser.