A Uniform Property Region Method for Screw Compressor's End-Face Leakage Prediction

Based on the assumption of a uniform property annular-shaped region at the labyrinth entrance, this paper proposes a method for leakage flow rate prediction at the discharge end-face of twin-screw compressors. Assumption of such a region is the key aspect in the construction of an equivalent network of end-face leakage flows, in which the labyrinth entrance zone is a node. Using mass and energy conservation laws, the thermo -physical properties of the average-state region (ASR) , and leakage paths flow rates are determined. The method is validated against experimental data obtained on an oil-free twin-screw compressor working with an ammonia-water mixture. The method allows for identification of additional leakages into cavities that are at the beginning of the compression process. Consequently it improves the accuracy of previous models.