Review and collection of preliminary design rules for low solidity diffusers

Authors

A. Grönman, J. Backman - Lappeenranta University of Technology, Finland
F. Dietmann, M.V.Casey - University of Stuttgart, Germany

Abstract

Low solidity diffusers are sometimes used in radial compressors where they promise a wide operating range close to that of vaneless diffusers but with efficiency levels that approach those of vaned diffusers. A literature survey has identified that despite the large number of papers on this subject there are no simple guidelines available for their design. However, general guidelines can be drawn for some of the design parameters from the available research data. Additionally, this paper proposes some simple design guidelines based on classical diffuser design parameters, such as length-to-width ratio and area ratio, whereby these parameters need to be specially defined in the case of very low solidity diffusers where the blades do not overlap. Experimental diffuser data is supported with 1D diffuser calculations to suggest suitable design guidelines.