The Current State of the Engineering Method for the Optimal Gas-Dynamic Design and Calculation of Centrifugal Compressor

Abstract

In the practice of centrifugal compressor designing, different engineering techniques are widely used because flow motion differential equations cannot be integrated, and Computational fluid dynamics cannot resolve the problem as a whole. Engineering personal computers’ programs are based on experimental data and the gas dynamics theory. The universal modeling method’s (UMM) mathematical model is a set of equations that determine the pressure loss in the elements of the centrifugal compressor flow path. By the earlier versions of the UMM, dozens of process compressors were designed. Several sets of empirical coefficients for stages of different specific speeds were applied. The paper presents the current state of the universal modeling method that was recently improved. The models of the centrifugal compressor characteristic calculation are described. A new model of the loading factor characteristic, an improved version of the compressor efficiency, and being based on a CFD-calculation vaneless diffuser model are samples of the improvements. Careful identification and verification demonstrate effective characteristic simulation with a single set of empirical coefficients. Centrifugal compressor new design examples of a turbo expander unit and a turbocharger are presented. The calculated characteristics are compared with the test results. For both objects, the experiments confirmed the calculated gas-dynamic characteristics with sufficient accuracy for engineering methods.