Centrifugal compressor stages efficiency analysis by means of the approximate algebraic equations

The specified design parameters of a centrifugal compressor can be provided with different number of stages, diameters of impellers, types of diffusers, rotor speed. The Universal modeling method by prof. Yu. Galerkin showed its effectiveness in the optimal design of dozens of types of compressors for a number of domestic and foreign manufacturers. In the case of a candidates’ calculation, the efficiency of the stages is calculated approximately from the system of algebraic equations developed in the mid of-1990s. The paper presents the modernized version of the system of 7 equations with 20 empirical coefficients. The coefficients approximate the results of model stages’ tests and designed stages, the efficiency of which was calculated by the precise mathematical models. A small computer program presents a possibility to calculate the efficiency and pressure ratio of the stages for which the gas dynamic design parameters, similarity criteria and design constraints are selected. The samples of the influence of the design parameters on the efficiency and the ratio of the stage pressures are given. The system of equations is integrated into the 7-th version of the computer programs of the Universal modeling method.