•Screw compressor performance may be reasonably well predicted by often-used one-dimensional models. It is assumed in most of these models that:
- both main and leakage flows are one dimensional,
- dynamical losses are effective especially in case of inlet and outlet flows
- temperature distortion effects are negligible
- due to centrifugal effects, the oil, when injected, passes through the machine almost exclusively in contact with the casing bore surfaces, •However, performance of a screw compressor is affected by:
- temperature and pressure distribution across the compressor,
- this causes the rotors and housing to distort,
- which has the reverse effect to the flow such that the clearances within compressor are changed
- which changes the leakage flow through the gaps.
- Additionally, such deformations can cause rotors wear and in extreme cases complete compressor failure. •Computational Fluid Dynamics (CFD) is widely used for the estimation of a fluid and thermal flow in rotating machinery. However, to deal with both fluid flow and thermal analysis as well as with component distortion where simultaneous flow and stress calculations are required some kind of Computational Continuum Mechanics (CCM) analyses is required.

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