Methods of Calculating Loading Factor Characteristic of a Centrifugal Compressor Impeller

Loading factor at design point is calculated by one or other empirical formula in classical design methods. The problem of the whole loading factor performance modeling was out of consideration. Test data on compressor stages demonstrate that loading factor function versus flow coefficient at an impeller exit is of linear character independent of compressibility. Known Universal modeling method exploits this fact. Two points establish the function - loading factor at design point and at zero flow rate. The proper formulae include empirical coefficients. Good result of modeling is possible if choice of the coefficient is based on experience and close analogs. Earlier Y. Galerkin and K. Soldatova have proposed to define a loading factor performance by the angle of its inclination to the ordinate axis and by the loading factor at zero flow rate. Simple and definite equations with four geometry parameters were proposed for loading factor performances calculated for non-viscid flow. The authors of this publication have studied test performances of fifteen stages of different type and ways of modeling. The equations are proposed with universal empirical coefficients. The calculation error lies in the range 1,5% of a loading factor at a design point. The alternative model of a loading factor performance modeling is included in new versions of the Universal modeling method.