Effect of tip clearance on the performance of self-priming vacuum pump

Tip clearance between the screw rotor and rotor housing in self-priming vacuum pump is an important factor affecting the performance of the pump. In this study, the effect of asymmetrical tip clearance on the performance of self-priming pump was numerically investigated with various values of aspect ratio of lower tip clearance and upper tip clearance in rotor housing. Numerical analysis was also performed with various rotational speeds (1550, 1650, 1750, 1850 and 1950 RPM) by using commercial code, ANSYS CFX. The results for pressure distributions, velocity vector and characteristic curve were graphically depicted with different aspect ratios of lower and upper tip clearances.