Numerical Simulation And Optimal Design Of High Specific Speed Self-priming Centrifugal Pump

This subject belongs to the national high technology research and development program(863 program) "precise irrigation technology and products" one of the research contents of project for precise control technology to agricultural efficient water use and the products(project number: 2011 AA100506).High specific speed self-priming centrifugal pump driven by diesel engine, air compressor and pump shaft linkage without bottom valve and external vacuum pump. it starts without irrigation water pump properly. Innovation of system and the structure of self-priming form to ensure the high specific speed self-priming performance of self-priming centrifugal pump efficiency. This pump can be used to solve large irrigation water supply problem of northwest, northeast and other regions, at the same time also play a key role in flood control and drainage for urban drainage or mining drainage, etc. From the numerical simulation and optimization of ratio speed self-priming pump design direction, the main research work and innovation points are as follows:(1)Hydraulic design for high specific speed self-priming centrifugal pump. According to the requirement of the subject, designed the flow components for the pump, adopting the closed type and spiral twisted impeller pressurized water chamber, gives a detailed description of the parts of the design process and design result, and is trying to draw hydraulic drawing.(2)Design for the innovative self-priming system of high specific speed self-priming centrifugal pump. Designed a new type of self-priming system, to ensure it complete self-priming efficiently. Main self-priming parts include: the air compressor, the jet nozzle, the coupler clutch, and the check valve. The main mechanism is the compressed air form the compressor brings negative pressure to the pump cavity, gas-liquid separation chamber check valves open, the compressed air mixed with the pump cavity gas continuously, and is discharged from the nozzle, until the import of pipeline gas is dry, pump to start to work normally.(3)Numerical simulation of inner flow field for high speed self-priming centrifugal pump. Used the CFD software to simulate the whole flow field for high speed self-priming centrifugal pump and analysis the internal flow field distribution for high speed self-priming centrifugal pump running in 0.6Q, 1.2Q, 1.0Q, 0.8Q.Calculate the head, efficiency and shaft power for each point,predict hydraulic performance for high speed self-priming centrifugal pump, at the rated head design point,the simulation value of H is 45.98 m, the efficiency of the simulation values for η is 73.15%, meet the design requirements.(4)Research of cavitation characteristics for high specific speed self-priming centrifugal pump. On the basis of numerical simulation result for the single-phase self-priming centrifugal pump, by loading the cavitation model on its internal cavitation flow numerical simulation. Predict cavitation occurs under different flow characteristics of internal flow field under different working conditions, analysis cavitation performance of high speed self-priming centrifugal pump. With the loss of the device for cavitation allowance, the cavity size distribution within the pump increases, cavitation first appeared at the edge of the blade on the back of the import, and spread along the direction of blade back toward the exit, along with the increase of flow rate, the cavitation performance get worse.(5)Experimental research for high specific speed self-priming centrifugal pump. Test and research for external characteristic of high speed self-priming centrifugal pump, in the rated design point, the capacity is 502.44 m3/h, head is 45.22 m, efficiency is 72.79%, the error between the numerical result and the experimental results is very small, the numerical simulation can accurately response the internal flow of the pump.