| Pumping station with low head plays an important role in our country cross-basin water transfer,water environment improvement,urban flood control and other aspects.The efficiency of pump system is determined by its productiveness of each part and their smoothness of mutual connection.The guide vane plays a role of connecting impeller upwards and outlet conduit downwards.The original intention of setting guide vane in impeller outlet is the conversion of rotatory kinetic energy to pressure energy,and reduce hydraulic loss.At present,the guide vane can be not adjusted.Inlet angle of guide vane is determined by the velocity triangle of the flow in runner outlet at the design condition.The design goal of the outlet of guide vane should be to obtain optimal circulation which makes the outlet conduit get the optimal hydraulic performance at the exit of guide vane.Optimal circulation associated with the flow.The velocity triangle of the flow in runner outlet and the outlet conduit's optimal circulation will change when conditions change.The guide vane's inlet and outlet angles can not be adjusted right now and the Hydraulic loss will increase.In case of that,the pump assembly efficiency will decrease.For increasing the pump assembly efficiency,this paper come up with a method that we can adjusted the guide vane's inlet and outlet angles.Focus on how the guide vane's inlet and outlet angles affect the pump system's hydraulic performance,research work in this paper mainly include the following contents:1 Has been clear about the meaning and the purpose of the main research content of how the guide vane's inlet and outlet angles affect pump hydraulic performance,by summarizing and analyzing Axial flow pump at home and abroad research achievements of the rear guide vane.Meanwhile,in this paper has been summarized and analyzed the development status of numerical simulation to choose this paper's research method and its feasibility.2 Model the axial flow pump system and mesh this model.To ensure that the grids have no effect of axial flow pump hydraulic performance calculation result,we have done simulation calculations of axial flow pump system models with different calculation grid number.And on this basis,we use CFD software to calculate different schemes and analyze the simulation results.3 Overall adjustment method of the guide vane is put forward and simulating calculations in different pump operating point were carried out.When flow is 0.8Qd,0.9Qd,1.0Qd,1.1Qd,1.2Qd with the fixed guide vane,the pump assembly efficiency is 72.06%,75.33%,74.96%,65.59%,38.84%.When the guide vane is overall adjusted,the optimal pump assembly efficiency can be 74.02%,75.81%,74.96%,66.20%,43.24%with different flow.So,we think that overall adjustment of guide vane can improve pump assembly efficiency.4 With 0.8Qd and 1.2Qd which is small flow and big flow,this paper gives a separate analysis the effects of guide vane's outlet angle to outlet conduit's hydraulic performance.We give the idea of branch adjustment guide vane and simulating calculations were carried out.Based on the above,one can draw a conclusion that different adjustment methods of the guide vane have a great influence on pump hydraulic performance when the flow is small.The optimal pump assembly efficiency with overall adjustment method is improved by 1.96%than the fixed guide vane.The optimal pump assembly efficiency with branch adjustment method is improved by 1.16%than the overall guide vane.When the flow is big,overall adjustment method of the guide vane have a great influence on pump hydraulic performance.The optimal pump assembly efficiency with overall adjustment method is improved by 4.4%than the fixed guide vane.Branch adjustment method of the guide vane have a lesser influence on pump hydraulic performance than overall adjustment.The pump hydraulic performance is only improved by 1.16%. |
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