Definition of a CFD Methodology for the Development and Optimization of a Scroll Compressor

During the last five years, scroll compressors have become very popular in refrigeration and air conditioning (products) devices/machinery due to their efficiency and low vibration. Another important aspect that characterizes scroll technology is that during gas compression no lubricant oil passes through the gas/pump chamber. Currently, scroll technology is being used as an oil-free vacuum pump – this sentence might just as well be eliminated or added to the body of your essay b/c it seems a bit out of place here, doesn’t really add to your argument. Every scroll pump consists of two involutes engaged/paired with an offset of 180 degrees. During the compression it is possible to identify gas pockets whose sizes and shapes change continuously from suction port to discharge port, according to the involutes profiles.. Modifying the involute profile is possible to drastically increase the scroll performance. First of all, to optimize the overall performance of a scroll compressor, a design optimization process of the involute profiles is necessary; today it is possible by using Computer-Aided Design (CAD) and Computer Manufacturing Approches (CAM) tools. On the other hand, for a scroll compressor, the only mechanic optimization by CAD-CAM instruments can't be considered adequate. In fact, to improve the performance and reliability of a scroll compressor it is necessary to clearly understand the three-dimensional gas fluid dynamic evolution inside the pockets during the compression phase. To obtain detailed information about the fluid dynamic behaviour of the gas inside the pockets, an experimental approach is not advisable because of the difficulties in the positioning of the experimental probe points on the real machine. The best way to perform a detailed fluid dynamic analysis of a scroll machine is to define a numerical methodology using the Computational Fluid Dynamic (CFD) tools. The aim of this paper is to show a numerical three dimensional CFD methodology defined and adopted to optimize the fluid dynamic behaviour of a new scroll vacuum pump. The CFD methodology has been defined by using the CFD commercial code Fluent v6.3 and the changes of the pockets geometry during the compression phase have been modelled adopting a 2.5D moving approach. All the components from the inlet to the outlet section of the scroll compressor have been considered during the CFD simulation.