CFD Modelling of a Twin Screw Expander Using a Single Domain Rotor Grid

摘要

Grid generation for analysis of screw machines plays a significant role in the accuracy of Computational Fluid Dynamics predictions. Recently a new grid generation method, referred to as Casing-to-Rotor conformal mesh, was developed to generate fully conformal single domain mesh for the working domain between screw machine rotors and casing. In this work, an analysis of the performance prediction of a twin screw air expander with this novel single domain mesh generated in SCORG is compared with the results obtained with the mesh consisting of two domains and measured results obtained on the test rig. All grid generation techniques are available in SCORG and their mathematical background is presented in this study. Stationary grids of the ports are generated using ANSYS commercial grid generator. The CFD calculations were performed in ANSYS CFX solver. The simulations with the various grid techniques are compared with the experimental data from a twin screw expander obtained from a recent study. The results of this study show the impact of the grid generation on the prediction of the expander performance and confirm that the Casing-to-Rotor conformal mesh is recommended for use in modelling of screw expanders.