Based On The Impeller Design Is65-type Centrifugal Pump Cavitation Performance Improvement

Cavitation is a harmful physics phenomenon, which does harm to the normally running of centrifugal pump, taking liquid as service fluid, and the condition of cavitation function is closely related with the designing condition of the impeller. During the running of the impeller, water power function of the IS65 impeller is analysed, distribution functions of pressure and velocity are calculated in the inner flowing field, and the reasons of the cavitation in the impeller is analysed, by using of the relevant hydromechanics knowledge. The designing defecting of the blade in the form of three arcs cylindrical surface in the IS65 impeller that the different relative motion stream faces are intersected each other is pointed out, which causes the pressure and velocity to be undulated and the lquid to be cavitated in the field.Numerical simulations of centrifugal pump fixed the IS65 impeller run under the condition of designed rate of flow are carried out, after the theoretical analysises are finished. During the numerical simulations, the grid model of the centrifugal pump is constructed with the gambit software, and the model is inputted into the fluent software to be simulated. The result of the numerical simulation shows the minimum absolute pressure and the maximal absolute pressure in the inner flowing field of the impeller takes place the long amplitude's pulsations with the time counting. When the minimum absolute pressure is pulsated, the value of the minimum absolute pressure is decreased greatly and less than the cavitation pressure of the working liquid, which makes the working liquid cavitating and transfoming from the liquid state to the vapor state. So the cavitation of the working liquid is related with the pressure's pulsation, which is consistent with the result of the theoretical analysises.The inverse problem improving design of the IS65 impeller is taken according to the analysises of the cavitation's reasons of the IS65 impeller, the designing methods takes the three-dimensional designing method based the S2m stream face and velocity modulus designing method, and some parameters in the original design are used to the improving design. The main purpose of the improving design is to improve the blade's form. After the new blades are designed, the distribution characteristic property of pressure and velocity are analysed in the inner flowing field of the running impeller, which is fixed the new blades. The analyzing result shows the function of the new impeller is good to the running performance of the pump.After the theoretical analysises of the new impeller are finished, the grid model of the centrifugal pump, fixed the new impeller, is constructed with the gambit software, and inputting the model into the fluent software is to be simulated. Numerical simulations mainly simulated the pump running function under the condition of designed rate of flow. The result shows the new impeller can well satisfy the running demand of the pump, the minimum absolute pressure and the maximal absolute pressure in the inner flowing field of the impeller changes stably with the time varied, not taking the long amplitude's pulsations. In the pressure field, the cavitation is difficult to be taken place, so the cavitation function of the pump is improved.Finally, the whole researching procedure is summed up, the deficiencies in the analysises and calculation are pointed out, and the further research working of the future is looked into.