The Optimization Design On High Head Centrifugal Pump For Agricultural Irrigation

Because of the special geographical position, the low specific-speed centrifugal pumps are widely applied to agriculture irrigation in mountainous area in south of China. They are equipped with the feature of high head, light weight, small volume and simple structure and so on. However, three big problems can be often seen in the low specific-speed centrifugal pump:The efficiency is low, The head curve humps easily and The horsepower overload easily. Especially, the third problem has been a threat to the security of users.In order to deeply study the overloading problem about the low specific-speed centrifugal pump, this paper chooses a group representative parameters as the design sample and make the research systematically from three aspects that theory analysis, hydraulic design and numerical simulation; then, The centrifugal pump main structure parameters are optimized, and its performance is forecasted based on the numerical simulations. The main contents includes as follows:(1) The article not only introduces all kinds of hydraulic design methods and their advantages and disadvantages, but also summarizes the general design principle of selecting the structural parameters about over-current components of pump. A discussion on the relationship among high head, high efficiency, no hump and non-overload has been made and it is believed that they can work together. The effect of the overflow part geometric parameters on the characteristic curve of centrifugal pump are analyzed, and we can take the measures that decreasing theβ2、b2、Z、F1and increasing D2to eliminate the overloading and the hump zone of H-Q characteristic curve.(2) Non-overload design method has been put to use to make the centrifugal pump arm with the non-overloading characteristic. And now the over-current components geometric parameters and the hydraulic design drawing have been worked out. At this time, the three-dimensional solid models of impeller and volute could be established by making use of the parameterization UG software before importing them into the GAMBIT and meshing them; then it is necessary to import the generating mesh data files into the FLUENT and we can obtain the useful information from the internal pump flows by numerical calculation. (3) The theory about the equations of controlling the fluid motion which is within centrifugal pump, turbulence models and boundary conditions has been represented briefly. The essay also has described three methods to predict the performance of centrifugal pump and made analysis and comparison between them. Based on three-dimensional flow-filed numerical calculation of centrifugal pump coupling impeller with volute, the pressure and velocity distribution coming from the fluid motion in internal pump has provided centrifugal pump optimization design with references information, and what’s more, directed the way to improve the pump structure.(4) Compared with the theoretical analysis results of pump actual motion, the inner flow state which is based on the FLUENT numerical calculation keeps the same trend generally. It indicates that the non-overload design example of the paper is reasonable and has a certain reference value and guiding significance.(5) Finally, the paper points out the shortages in research and puts forward the directions to research work in the future.