AN EULER-BASED THROUGHFLOW APPROACH FOR CENTRIFUGAL COMPRESSORS - PART A: EXTENSION AND MODIFICATIONS OF MODELS

This paper presents the extension and validation of an Euler-based throughflow solver for the analysis of centrifugal compressors. The conservation equations are augmented with aerodynamic models suitable for describing a centrifugal compressor. The paper analyzes the impact of the varying meridional pitch angle on the blade force model and proposes two different approaches to consider this variation in the calculation. Further, the paper includes the development and implementation of additional loss models based on enthalpy loss coefficients, which take into account the different loss mechanisms in centrifugal compressors. In this contribution, the modifications are introduced and discussed. To validate the modifications, they are implemented in an existing Euler-based throughflow solver called tFlow. First, the extended solver is compared with the results of computational fluid dynamics (CFD) and calibrated with respect to the total efficiency at the design point. The resulting performance values predicted by the extended solver at off-design conditions are in good agreement with the CFD results. Subsequently, in Part B of the paper, experimental data is used to validate the predicted performance values of the extended solver. The experiments are carried out on a centrifugal compressor test rig described and explained in detail in Part B of this paper. The performance values predicted by the extended solver are in good agreement with the experimental data with respect to the pressure ratio.