Centrifugal Compressor Stage. Vaneless Diffuser Preliminary Design By Universal Modeling Method

Most often, industrial centrifugal compressors use two-section vaneless diffusers:a tapered inlet section and à constant-width main section. The authors propose to choose such a width of the main section, at which the flow in the diffuser remains non-separated at the surge limit. To implement the primary design method, an empirical equation of the minimum non-separated flow angle versus the relative width of the diffuser, and the number of other equations are proposed. The primary design of 18 stages in a practically important range of parameters was carried out, their characteristics were calculated by the Universal modeling method and the sizes and flow angles were analyzed. The method for calculating the diffuser dimensions is integrated into the Universal modeling method and is used in design practice