The CFD Analysis of a Screw Compressor Suction Flow

Dynamic flow losses in the suction chamber are a significant factor in reducing screw compressor efficiency but can only be roughly estimated in compressor design due to the simplified methods of analysis used to account for them. Today, Computational Fluid Mechanics analysis may be used to estimate velocity, pressure, temperature and concentration fields within a screw compressor far more accurately. This technique can thus be employed to design a suction port with minimised flow losses. The paper describes the application of a CFD procedure to calculate screw compressor suction flow. A numerical grid of the suction chamber was generated by a 2-D transfinite interpolation combined with the layer meshing technique. This was used to develop an independent and stand-alone interface program which connects the screw compressor geometry to a conventional numerical pre-processor. Typical results arising from its use when linked to Comet, a commercial CFD solver, are shown for an oil-flooded screw compressor.