Experimental and theoretical analysis of the flow in a centrifugal compressor volute

Detailed measurements of the swirling flow in a centrifugal compressor volute with elliptical cross section are presented. They show important variations of the swirl- and throughflow velocity, total and static pressure distribution at the different volute cross sections and at the diffuser exit. The basic mechanisms defining the complex 3D flow structure are clarified. The different sources of pressure losses have been investigated and used to improve the prediction capability of one dimensional mean streamline analysis correlations. The tangential flow loss model, under decelerating flow conditions, and friction loss model are confirmed. New emprical loss coefficients are proposed for the exit cone loss model and the tangential flow loss model for the case of accelerating flow in the volute.