Development of a method for geometric modeling of centrifugal compressor impellers

Abstract

The practice of designing centrifugal compressors in which impellers are the main components shows that there are reserves for their further improvement. One of the main reserves consists in improving flow conditions for the compressed medium in the compres­sor flow path and, above all, in the impeller. A method of geometric modeling flow path of the impellers of centrifugal compressors was proposed which involves the construction of meridional boundaries of impel­lers and the blade profile on an involute of the cylin­drical surface of the outer radius of the impeller. The blade is represented by ruled surfaces. The shroud of the impeller is described by a curve in natural parame­terization using cubic dependence of curvature on the arc length. Dependences and length of the arc are determined in the process of modeling the boundary based on the set source data. The problem is solved by minimizing deviations of intermediate curves from the boundary endpoint. The hub is obtained as an enve­lope of circles inscribed in the meridional channel of the impeller. Radii of the circles are determined taking into account the flow areas of the channel. The camber line of the blade profile on an involute of the cylindrical surface of the outer radius of the impeller is modeled using a curve that is presented in natural paramete­rization with quadratic law of curvature distribution. A computer code was developed in the Fortran Power Station programming environment that visualizes the obtained numerical results graphically on a compu­ter display in addition to digital information on the modeled boundaries and the blade profile. Graphical results were presented. They confirmed the efficien­cy of the proposed method of modeling the flow path of centrifugal compressor impellers. The method can be useful to offices involved in the design of centrifu­gal compressors