Experimental study on the optimal range on nozzle-to-throat clearance of jet centrifugal pump

Abstract

There has been a general recognition that the distance between the nozzle and the throat can affect the self-priming performance of the jet centrifugal pump. Although previous studies have been made to determine the range of the distance based on the method of numerical analysis, the approach of self-priming experiment has been seldom used. This paper presents the optimal range of this distance with the experimental measurements. A UJM100 jet centrifugal pump manufactured by a company in Zhejiang was used to complete the self-priming experiment. The nozzles with the diameter of 7mm, 8mm, and 9mm were used respectively to work with the the diameter of 15mm throat and the nozzle-to-throat clearance based on a original formula which denoted the relation between area ratio and the nozzle-to-throat clearance. The scheme with optimal self-priming and hydraulic performance was selected from the three schemes mentioned above. And this selected group should be adjusted the clearance of nozzle-to-throat to find out the optimal range. Finally, the changes of jet centrifugal pump’s self-priming performance which were modified were analyzed within the usage of experimental measurement. As a result, the nozzle-to-throat clearance of this kind of pump exists a optimal range while the area ratio was in a certain scope. The scheme with the diameter of 9mm nozzle and the diameter of 16mm throat which can obtain the optimal self-priming performance was ascertained by experiment. Based on the tests, the value of the nozzle-to-throat clearance was selected at the range of 8.5mm to 9mm. According to the experiment, the relation between area ratio and the nozzle-to-throat clearance was modified to a new formula.