Scroll, Compressor, CFD, Deforming Grid
Scroll compressors are widely used in many industries. It is considered that scroll compressors have the advantage of high efficiency, lower noise and vibration levels. There are various losses in a scroll compressor that need to be studied to achieve better efficiency, of which the most significant is the flow losses, especially the losses at discharge. Computational fluid dynamics (CFD) simulations can be a useful tool in understanding the flow field and help reduce the flow losses through design optimizations. There are few numerical studies on the flow inside the scroll compressor. The reason is that defining the mesh and its movement in the scroll rotor can be demanding. The flow field of a scroll compressor is unsteady and 3-dimensional, consisting of gas pockets with changing geometry and volume. More often than not, check valves are used at the discharge to prevent reverse flow, which complicates the setup of the numerical simulation. The present work demonstrates a newly developed rotor template tool for scroll compressors/ expanders. This scroll template generates high-quality structure mesh from the outlines of stationary and orbiting rotors, which are input from the user. The mesh movement is also automatically calculated to account for every position of the orbiting rotor, maintaining good grid quality and smooth movement through the whole revolution. The tool greatly simplifies the setup of the CFD simulation and can significantly reduce turn-around time. Moreover, the check valve is simulated with the flip valve template tool. Here, the bending deformation of the flexible reed valve plate is replaced by a rigid body rotation. With judicious choices of torsional elastic constant and preload torque, the valve opening at the center of the discharging port can be setup to mimic that of a flexible flap. The rotor and valve components are then combined, to provide a complete solution for scroll compressor/ expander flow simulations.