Flow visualization at suction of a twin screw compressor

Rotary twin screw machines are commonly used for handling single and multiphase fluids in industry as compressors, expanders and pumps. Liquid concentration in the admitted gas can influence the performance of the machine significantly. The flow characteristics of the liquid phase depend on its concentration and may also affect the ability of the machine to handle it without getting damaged. Experimental techniques enable single and multiphase flows to be observed and measured but are difficult to control. It is therefore useful to develop models to predict the flow and performance of multiphase screw machines.
The £D Computational Fluid Dynamics (CFD) is used in this paper to investigate the effect of water injection into the air stream at the inlet of an oil free screw compressor. The CFD results were compared with measurements of the flow pattern obtained from a high speed camera. The agreement between them is sufficient to justify the use of CFD for further investigation of multiphase flow in the suction of the compressor.