CFD simulation of a screw compressor including leakage flows and rotor heating

9th International Conference on Compressors and their Systems

Spille-Kohoff, Andreas^1 ; Hesse, Jan^1 ; Shorbagy, Ahmed El^1

CFX Berlin Software GmbH, Karl-Marx-Allee 90A, Berlin

10243, Germany^1

关键词: Computational fluid dynamics simulations;    Deformation simulation;    Development process;    Dry screw compressor;    Hexahedral meshing;    Positive displacement;    Thermodynamic behaviour;    Turbulence effect;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/90/1/012009/pdf
DOI  :  10.1088/1757-899X/90/1/012009

来源: IOP

【 摘 要 】

Computational Fluid Dynamics (CFD) simulations have promising potential to become an important part in the development process of positive displacement (PD) machines. CFD delivers deep insights into the flow and thermodynamic behaviour of PD machines. However, the numerical simulation of such machines is more complex compared to dynamic pumps like turbines or fans. The fluid transport in size-changing chambers with very small clearances between the rotors, and between rotors and casing, demands complex meshes that change with each time step. Additionally, the losses due to leakage flows and the heat transfer to the rotors need high-quality meshes so that automatic remeshing is almost impossible. In this paper, setup steps and results for the simulation of a dry screw compressor are shown. The rotating parts are meshed with TwinMesh, a special hexahedral meshing program for gear pumps, gerotors, lobe pumps and screw compressors. In particular, these meshes include axial and radial clearances between housing and rotors, and beside the fluid volume the rotor solids are also meshed. The CFD simulation accounts for gas flow with compressibility and turbulence effects, heat transfer between gas and rotors, and leakage flows through the clearances. We show time- resolved results for torques, forces, interlobe pressure, mass flow, and heat flow between gas and rotors, as well as time- and space-resolved results for pressure, velocity, temperature etc. for different discharge ports and working points of the screw compressor. These results are also used as thermal loads for deformation simulations of the rotors.