Numerical Simulation Study About Influence To The Performance Of Centrifugal Pump From Rotating Speed Change And Energy Saving Analysis About Speed Regulation Method

In engineering practice, the adjustment of working point for centrifugal pump is very common. And in several adjustment methods of centrifugal pump, the energy-saving advantage of speed regulation method is very obvious. This requires us to study the changes of internal flow field and performance parameters as the pump speed changes, in order to improve the existing semi-empirical theory and guide the practical production. Meanwhile, for some high-power pump, limited to the laboratory capacity, the power of drive motor and other conditions, the full speed experiment can not be performed. And the performances of pump in full speed are got by the conversion of scaling law after deceleration experiment. Therefore, the accuracy of scaling law plays a vital role, and it is necessary to verify the accuracy of scaling law and scope of application, in order to provide a reference for the practical application.For this purpose, this paper selected single-stage double suction centrifugal pump that widely used in practice as the research object. After that, the numerical simulations were made in 5 similar working point groups at 8 different speeds. Then the changes of internal flow field and external characteristics were compared. Finally, calculate the energy saving effect of pump speed adjustment were calculated. The main work and research results of this paper are as follows:1. The three-dimensional model of selected double-suction centrifugal pump was established, then the mesh was drawn in this model. And by using Fluent software, the numerical simulations were made in the whole flow passage.2. After the post-processing of simulation results, the pressure and velocity contours of chamber and blade were obtained. By comparing the pressure contours, it was found that the pressure distributions of chamber and blade are very similar and almost identical in similar operating point, which means that the dynamic similarity in flow field of the pump can be achieved, and the numerical simulations of this pump is mainly right. By comparing the velocity contours, it was found that the velocity distributions of chamber in similar operating point at 0.7n, 0.9n, 1n, 1.1n, 1.2n, 1.3n are almost the same velocity distribution, while the velocity distributions in 0.6n, 0.8n are slightly different with others. But the velocity distributions in both front and back of blade are very similar. Overall, the velocity distributions of chamber and blade are still highly similar, which indicates that the kinematic similarity in flow field of the pump can also be achieved.3. The performance parameters were predicted by both numerical simulation results and scaling law. After comparing those results, it was found that the scaling law can accurately predict the changes of pump performance parameters when rotational speed changes. And for the 5 similar working point groups this paper selected, the error of scaling law in most operating points are less than 1% , so the scaling law van meet the actual needs for this pump.4. Analysis of the energy conservation principle and the factors influencing energy saving effect were made, and energy-saving effect was calculated in particular pump network. Then it is found that speed adjustment method has a good energy saving effect, and the energy saving effect is more obvious as adjustment is increased and, when the pump runs at low flow, the saving rate can be up to 74.58%.