Parametric study of centrifugal compressor stage vane diffuser characteristics by CFD methods

摘要

The paper presents results of CFD simulations of a series of centrifugal compressor stage vane diffusers in the Ansys CFX. Objects of research are vane diffusers with external relative diameter (relative to the diameter of the impeller) equal to 1.5, vane inlet angles of 15, 20, 25 and 30 degrees, relative vane heights of 0.025, 0.045, 0.06, 0.08, vane profile curvature angles of 10, 15, 20 degrees. The characteristics of the polytropic efficiency, the loss coefficient, the recovery coefficient, the inlet-outlet velocity ratio, the flow deviation angle depending on the incidence angle are calculated. The analysis of the flow pattern in the intervane channel is presented. Increasing the vane curvature angle leads to a diffuser characteristics shift to the area of negative incidence angles. The flow deviation angle is almost independent of the diffuser width and increases with the curvature angle. In most calculations, a narrow diffuser (0.025) shows higher values of characteristics in the area of positive incidence angles. Characteristics of diffusers with a large inlet angle (25-30°) do not have a strong maximum.