Screw Machine, Clearance Investigation, CFD
Chamber model simulation is a common approach for the simulation of positive displacement machines. For this kind of simulation the clearance mass flow is usually predicted using an isentropic approach, which is corrected with a flow coefficient in order to picture the real flow conditions and the corresponding mass flow. The detailed knowledge of the flow coefficient and its dependencies is crucial for a meaningful simulation of positive displacement machines. This paper investigates the two-dimensional fluid flow through the front clearance of twin screw compressors using the finite volume method. Dimensionless numbers are determined using the PI-theorem and are varied systematically in order to show their influence on front clearance mass flow rate. The results are therefore useful for any dry running application with similar clearance geometry, independent of the type of gas (e.g. heat capacity, viscosity) and operating conditions (e.g. pressure, temperature, rotational speed). Results for a non-moving wall are compared with experimental results.