Hydraulic Design And Experimental Study On Self-priming Performance Of Self-priming Pump

As one of the key elements in small irrigation systems, self-priming pumps are widely used in agricultural irrigation. In this study, a self-priming pump of 65ZB40-5.5D type is designed by using the velocity-coefficient method, and is manufactured. The experimental results demonstrate that this design is successful. In order to study the self-priming performance of self-priming pump, some experiments in different operating conditions are conducted. The relations between self-priming time and nozzle angle, nozzle diameter, gap from impeller outlet to volute separation tongue, size of water storage and diameter of suction pipe, are established.By careful design and performance test, main achievements are gained as follows: (1) The self-priming pump of 65ZB40-5.5D type is successfully designed to meet the design conditions in self-priming performance and hydraulic performance. (2) For low specific-speed and moderate specific-speed self-priming pumps, the nozzle angle has little influence on self-priming performance, and the optimal nozzle diameter isn't in proportion to the value of Q/n^1/3 . (3) For low specific-speed and moderate specific-speed self-priming pumps, the smaller the separation tongue gap is, the better the self-priming performance is. The separation tongue gap is commonly 0.5mm wide. (4)The self-priming performance is better when the water storage is one half of the rated flow, whereas the self-priming time becomes long when the water storage is greater than or less than it. (5)The relation between the self-priming time and the diameter of suction pipe is modified.The above results can be used to direct the design of self-priming pumps and improvement of self-priming performance.