EXPERIMENTAL STUDY OF VANED DIFFUSERS IN CENTRIFUGAL COMPRESSOR

Improving the performance of a centrifugal compressor can lead to decreased energy consumption in industry. Vaned diffusers are known to narrow the operating range but increase the peak efficiency compared to vaneless diffusers. In this study, three vaned diffusers and one vane less diffuser are studied experimentally to improve compressor performance. Attention is paid to the operating range and performance of the diffuser specially close to stall, and therefore the vaned diffusers are designed to have large negative incidence (-8 degrees) at the design conditions. Different vane numbers and vane turnings are used. Compressor performance maps are measured at different rotating speeds and diffuser flow fields at the design rotating speed. The results show that the vaned diffusers make the diffuser outlet flow field more uniform than the vaneless one. The peak efficiency of the vaned diffusers occur at lower mass flows, and the efficiency is also higher at the design operation point with the vaned diffusers. In general, the vaned diffusers are better at lower mass flows, but stall earlier.