CFD simulation of scroll compressors with axial and radial clearances and thermal deformation

Scroll compressors are positive displacement machines which compress the gas in size-changing working chambers while transporting it from the suction side to the discharge side. The working chamber size results from the movement of an orbiting scroll around a fixed scroll. Scroll compressors are used in the automotive industry for air-conditioning and turbochargers while scroll expanders are used for heat recovery systems.This paper shows transient 3D CFD results of a scroll compressor used as a dry scroll vacuum pump (DSVP) including clearance flow, turbulence effects and conjugated heat transfer between gas and solids. The setup steps and results for the simulation of a DSVP are shown and compared to theoretical and experimental results. The timevarying working chambers are meshed for each time step before the CFD simulation with special hexahedral meshing software for positive displacement machines which can handle small clearances around 10 μm. The CFD results are used for a mechanical simulation to get the thermal deformation of the scroll compressor. The deformation has an impact on the clearance size and can be used to optimize the CFD model.Numerical simulation is one important part of the scroll compressor development to get an optimized machine. By using special meshing software, high-quality simulations can be done capturing all clearance flow effects. Thermal deformation should be taken into account to get the clearance size depending on the operating point.