Research On Actual Pumping Speed Calculation Of Multistage Dry Roots Vacuum Pumps

With the development of electronic, chemical, film and freeze-drying industries, oil-free vacuum environment is needed by more and more industries as their processes conditions. Therefore, roots pump is more and more desirable in the market. When we estimate roots pump's performances such as ultimate pressure, we should precisely calculate the leakage of clearances. But now there're mostly experience formulas. When the pump works, its channel's size changes, rotors circumrotate, and we don't consider the effect of them to conductance. So there's a big difference between the values of theoretic and experiment.When the corporation design and produce a new pump, they usually carry through academic design based on technique requests firstly. Then they produce a sample to validate them. The difference between theoretic and experiment makes us to correct and improve on the design. Later they produce another sample to validate it. In this way we will certainly use up a mass of time and money. In this paper, the more accurate modeling and amelioration of roots pump's leakage is researched. We summarize the capability targets and their calculate method of roots pump. Some cases of clearance leakage are simply described. The topic is mainly on the building of the gap leakage model of the Roots pump, and to consider the deformation owning to the imbalance between the rotors and the impact on the gap owning to heat distortion of the body. at last, I finish the improvement on these factors.We introduce the rotor equations, character dimensions and mesh principles of circular arc, involute and cycloid. The leakage's calculation methods of these kinds of pumps are described on the base of ameliorated model.We can use some software and make use of higher mathematics to write calculation process to make the calculation easy. Then, we calculate the leakages and performances of a roots pump pattern. We should consider it in our later research. And they were compared and analyzed with the calculated values and the measured values which weren't amended before. The result indicates that the revised calculating method is preciser than traditional methods on the ultimate pressure.We calculate the leakage of root pump prototype, and then analyse the rotor and inner body part of Root pump in kinetics and thermodynamics by ANSYS software, figure out the axial and radial shape change of rotor in multi-field coupling, and figure out the temperature distortion and stress analysis of inner body part of pump. Then, we substitute the obtained result into calculation to get the revised actual pumping speed and compare it to the unrevised one.