Control of stall in a radial diffuser using rough surfaces

Abstract

Fluid flow instabilities in a compression system set the lower limit of the stable operating range, and choking sets the upper limit of the flow rate. Experiments to investigate the feasibility of controlling the stall in the radial diffuser of a low-speed centrifugal blower were carried out using a very simple technique that involved using rough surfaces (i.e., sandpaper) attached to the diffuser shroud. This choice was based on measurements which showed that the reverse flow occurred on the shroud side for the tested impeller with radial blades. The experimental data showed that the flow instability in the diffuser (stall) was delayed to a lower flow coefficient, which was about 70% of its value with the smooth surface. © 2008 CASI.