The Research on Performance for the Impeller Cutting of the Centrifugal Pumps with Low Specific-speed Based on the CFD
|School||Lanzhou University of Technology|
|Course||Fluid Machinery and Engineering|
|Keywords||low specific-speed centrifugal pump cut area ratio principle numericalsimulation pressure pulsation|
Usually,we defined the ns of the centrifugal pumps with low specific-speed is between thirty and eighty,this pump is widely used in the oil,chemical industry,and diggings field because of its small flow and high head characteristic. The flow of the centrifugal pumps with low specific-speed inside is very complex.the flow is full of the turbulence,it takes the vortical motion and it can not be press,so use the common experiment is very difficult to research its inside flow.At present,the CFD is used to analysis the flow of the pump,and is a very effective method.In order to achieve the performance demand of the centrifugal pump, expand the scope of the centrifugal pump,cut the outer diameter of the pump impeller is a way we usually adopted. The cut of the conventional method is selected the high performance centrifugal pump,and accordance with the current formula calculation, fixed, and then implement cutting. the Centrifugal pump impeller outside diameter will be changed after the cutting,and make its internal flow compared with prototype pump there are some differences. In this paper, A total of five times cut to the MH-47-100type low rotation speed centrifugal pump was carry out,and the characteristic curve was getted. After five times cut, each performance curve was analyzed and compared. Discussed the low speed centrifugal pump performance changes after the impeller diameter was cutted.In this paper, the mainly research for the MH-47-100type centrifugal pumps with low specific-speed is that:l:Cut the Centrifugal pump impeller outside diameter for five times,use the CFD carry out steady Numerical simulation to Each model.2:Calculated the area ratio of each model that before and after cutting, According to the existing literature that the high efficient area,get the conclusion that all of the models were fall into the high efficient area.3:Base the steady Numerical simulation, Did the unsteady numerical simulation to the the prototype pump, and after8mm and40mm cuted two models, Analysis under different pump impeller outer diameter the change of the flow.4:In the export of the impeller and the isolated tongue set up nine points, analyzes under the different diameter of the impeller export surface and volute outlet pressure pulsation. The mainly conclusions are obtained through the study is that:1:After the impeller outer diameter of the centrifugal pumps with low specific-speed with a small cut,the flow of its inside is similar;but after the impeller outer diameter with large cutting,the flow of its inside is no longer similar.2:After the impeller outer diameter with a small cut,the characteristic curve of the pump is relatively similar;and after large cutting,the characteristic curve of the pump is no longer similar.3:Through the phenomenon that the models were fall into the area of high efficient, Shows that the efficient to area of the statistical law have the certain reference value.4:After cutting the outer diameter of the impeller, the effect on the impeller of internal static pressure value is less than the centrifugal pump volute internal static pressure value,meanwhile with the increase of the cutting, the static pressure values of different points in the Pump were decreased.5:Through the unsteady simulation get the three models of different times pressure pulsation, And through the contrast analysis to get that, Impeller outside diameter reduced, Pressure pulsation intensity decreases.