Optimization of a Centrifugal Compressor Performance by Modification of Diffuser Geometry Using Inverse Design Method
This paper is concerned with a quasi-3D design method for radial and axial diffusers of a centrifugal compressor on the meridional plane. The method links up a novel inverse design algorithm, called Ball-Spine Algorithm (BSA), and a quasi-3D analysis code. The Euler equation is solved on the meridional plane for a numerical domain of which some unknown boundaries (hub and shroud) are iteratively modified under the BSA until a prescribed pressure distribution is reached. In BSA, the unknown walls are composed of a set of virtual balls that move freely along the specified directions called spines. The difference between target and current pressure distribution causes to deform flexible boundary at each modification step. In order to validate the quasi-3D analysis code, a full 3D Navier-Stokes code is used to analyze the existing and designed compressor numerically. The 3D numerical analysis of the current compressor show there is a huge total pressure loss on the 90-degree bend between the radial and axial diffusers. Geometry modification of the meridional plane causes the efficiency to be improved by about 10 percent.