Method of calculating axial forces in a centrifugal compressor based on a refined model of flow

Abstract

Most of the mathematical models used in methods of calculating the axial forces in a centrifugal stage of a compressor have been developed for fluid flow near a disk in a closed casing. In the absence of an outer cylindrical part of the casing, there is flow between the "open" disks, this being most characteristic for centrifugal turbomachines. The model of flow between the open disks should, as a particular case, include the flow of the medium in a closed casing and also correspond to experimental data on the flow structure. The generally used methods of calculating axial forces in a centrifugal stage have been developed on the basis of a three-layer model of flow of the fluid stream in the clearance between rotating disk and stationary wall as follows [i, 2]: a layer of quasi-solid flow is located between the boundary layers on the wall and disk, i.e., the core rotating at half angular velocity of the disk; discharge flow occurs in the boundary layers (Fig. la).