Development and identification of a mathematical model of centrifugal compressor stages using the universal modeling method

Abstract

The Universal Modeling Method is a complex of computer programs for calculating characteristics and optimizing design of centrifugal compressors based on mathematical models of efficiency and head. Practical experience allows improving mathematical models that underlie the Method. Determining the non-incidence inlet in a blade cascade is an important part of calculating the compressor gas-dynamic characteristics. In the 8th version of the Universal Modeling Method, a formula was used to calculate the direction of the critical stream line, containing an empirical coefficient X. The practice of application has shown that the value of the empirical coefficient changes the amount of losses in the impeller in off-design flow rates. A new scheme for modeling velocity diagrams was proposed. It was made for the stage operation mode corresponding to the zero incidence angle. The successful application of the model for the impeller design made it possible to extend it to the vane diffuser and return channel. Several other improvements were made, too. A new mathematical model was developed for calculating the flow parameters in the exit nozzles of centrifugal compressor stage. The mathematical model for calculating the flow parameters in the vaneless diffusers was modernized. The limit of applicability of the new model was expanded to a range of diffusers of low consumption stages with a relative width of up to 0.006. The resulting mathematical model was identified by the test results of two families of model stages and factory tests of industrial compressors.