RT Journal Article ID 6427fadd79c51136 A1 He, Ning T1 Steady and Unsteady Analysis of the Effects of Radial Gap Size in a Centrifugal Compressor Stage JF International Journal of Fluid Mechanics Research JO FMR YR 2007 FD 2007-02-02 VO 34 IS 1 SP 52 OP 65 AB In this paper, a computational analysis of a high-speed centrifugal compressor stage is presented. The main emphasis is placed on steady and unsteady investigations on the effect of different radial gap size between the leading edge of the vaned diffuser and the impeller tip on the detailed aerodynamics and the stage peak efficiency. The simulations were carried out for the stage with a backswept impeller and downstream vaned diffusers with different size of the radial gap. The impeller consisted of 8 full blades and 8 splitters and the downstream diffusers consisted of 22 vanes, with their leading edge at a radius of 1.075 and 1.150 times the radius of the impeller tip respectively. The steady and unsteady CFD analysis was carried out using the Reynolds-averaged Navier - Stokes solver CFX-TASCflow. For the steady state simulations, an averaging approach is used at the interface between the impeller and the diffuser. For the unsteady simulation, the method of geometry scaling is used in order to deal with the problem of unequal pitch. In this case one passage of the impeller was modeled in combination with three diffuser passages. The size of the radial gap influences considerably the detailed aerodynamic interactions in the vaneless and semi-vaneless space, the levels of unsteadiness and the amount of mixing occurring in this region. An important conclusion is that as the gap increases, the stage peak efficiency increases. The flow physics contributing to this result are quite complex and are addressed in the paper. The analysis was focused on impeller, vaneless space and vaned diffuser channel and comparisons with available experimental data are carried out. PB Begell House LK https://www.dl.begellhouse.com/journals/71cb29ca5b40f8f8,2fcb8e457ad5dfdd,6427fadd79c51136.html