This article focuses on the optimisation of the thermodynamic processing in dry-running screw spindle vacuum pumps using a computer-aided simulation system. The main aim of these investigations is to derive design criteria for the rotor geometry of the pumps. For selected profiles the influence of the geometrical design parameters on the operation facilities is examined and the optimisation of these parameters is described with the focus on thermodynamic processing. For the optimisation of compression during the transportation phase, various concepts for the rotor design are presented and advantages and disadvantages are discussed. A simulation system is used for analysing the influence of the design parameters, especially the thermodynamic parameters of the processing. The simulated operating characteristics are compared in order to derive design criteria. The investigation parameters cover the suction properties, the ultimate attainable pressure and the power consumption. The analysis of simulation results concentrates on the dominating influence of clearance flows inside the machine and at the inlet and outlet ports for all the different flow types (continuous, Knudsen, molecular).
展开▼
