Factors Impacting on Performance of Lobe Pumps: A Numerical Evaluation

Abstract

AbstractThe aim of current research is to investigate numerically the fluid dynamics of lobe pumps and typical factors which could impact on performance of the pump including profile of rotor surface, number of lobes, gap size between rotor and casing, and clearance between two rotors,etc. The circular and epicycloidal curves are used to generate profiles for rotor surface, while the complex flow phenomena inside the pump are simulated by dynamic mesh technique. With wide range of investigated speed from 1000 to 5000rpm, the study produces significant information on flow pattern, velocity and pressure fields. The advantage of epicycloidal pumps over circular ones has been demonstrated via characteristic curve which performs pressure head versus rotational speed. Meanwhile the analysis has proved that multilobes, three and four lobes, do not increase performance of the pump but provide more stable output and higher capacity compared with two-lobe pumps. The results confirm great impact of gap size between rotor and casing wall on the pump efficiency. Decrease of the gap from 1.25mm down to 0.5mm produces about 425% increasing of pressure head. In addition, it has been also proved that the clearance between two rotors could be varied from 0.12mm to 0.15mm without much effect on performance of the pump.