Validation of the Hydraulic Turbine Openfoam Library for a High-Pressure Centrifugal Compressor

Abstract

A special program module was added to OpenFoam more than 10 years ago, and a large number of studies have been devoted to its use for solving turbine engineering problems. Modeling inaccuracies can occur when the velocity is increased to supersonic flow. The aim of this work is to validate the OpenFoam open library of hydraulic turbines for the a high-pressure centrifugal compressor flow calculation and finding the parameters and calculation model that are optimal in terms of efficiency and total/total pressure ratio. For the numerical calculation, we used Reynolds averaging of the Navier-Stokes equations, which are used in the CFD library OpenFoam v. 2212. In this work, the two most commonly used turbulence models for such problems are used to close the equations of the mathematical model: the k-e model and the Shear stress transport (SST) model. The simulation was performed using a modified version of the sonicFoam solver, which is available in OpenFoam. The maximum error in calculating the total pressure ratio in the working zone for all models was 3 %. All models behave poorly in the low mass flow rate zone. The slope of all curves corresponds to the experimental characteristic. The calculation using the models with very fine meshes on average determines a 2 % increase in the total-to-total pressure ratio. Using OpenFoam, the integrated parameters of a high-pressure centrifugal compressor can be predicted accurately (maximum error does not exceed 5 %). The most accurate efficiency is predicted by the SST model using meshes of more than 2.56 million elements, but this number of elements is not enough to predict the compressor's performance at low flow rate zone. In further research, it is rational to use grids consisting of at least 5 million elements and use the SST turbulence model.