Comparison of methods for calculating thermal deformations of screw compressor rotors

At present time one of the most common positive displacement compressors used by different industries are screw compressors. It can be explained by their reliability, efficiency and easy servicing. However, there is still possibility to increase efficiency of screw compressors by improving their working process. It basically depends on the quality of their rotors’ profiles, which determines leakages between compressor working chambers. Usually it needs for the downward bias of one of the rotors actual profile in relation to the theoretical to compensate rotors’ thermal deformation, manufacture errors and other negative factors. Increasing the value of rotor profile downward bias reduces the compressor efficiency in general, at same time not enough value may lead to the rotors jamming during operation mode. Therefore, it is necessary to define actual thermal deformations of the rotors with high accuracy. To the comparison of rotors’ thermal deformation determining various methods the presented paper is dedicated.