Analysis on area utilization efficiencies of lobe pumps by deviation function method

This paper is to analyze the effects of several factors, including deviation functions, span ratios and numbers of lobes, on the area utilization efficiencies of rotor pumps based on the deviation function method. Four deviation functions are included, including two new deviation functions transformed from the previously proposed functions. Firstly, the applicable ranges of span ratios corresponding to the four kinds of deviation functions are presented. Results show that the maximum values of span ratios for the two new deviation functions are larger than that for the original functions. Moreover, compared with the original functions, the area utilization efficiencies of the two new functions are higher. Secondly, the area utilization efficiencies of the two-lobe profiles with different span ratios are compared. Results show that area utilization efficiency increases with the increasing span ratios. Finally, the effect of the number of the lobes on area utilization efficiencies is reported. Results indicate that the number of the lobes has a complex effect on the area utilization efficiency, dependent on the number of the lobe, span ratio chosen, and so on. Moreover, three kinds of pumps discussed (two-lobe, three-lobe and four-lobe pumps) are available for different span ratios. The conclusions found may give some references for designers when designing a rotor pump.