Flow Regimes in Two-Dimensional Ribbed Diffusers

Abstract

Water table flow visualization tests of a straight wall diffuser and corresponding ribbed diffuser were conducted over a wide range of total divergence angles and diffuser length to throat width ratios. Rib parameters such as inter-rib cavity depth to width ratio, inter-rib cavity width, rib thickness, and number of ribs were varied, as well as rib contour. Motion pictures were obtained of the secondary flow patterns occurring within the inter-rib cavities, and hot film measurements were made to determine the extent of velocity fluctuations induced by the cavities. In general, the addition of ribs increased the no-appreciable stall regime.