Study On The Optimization Of The Overflow Component Of The Guide Vane Hydraulic Turbine

As the country vigorously promotes energy conservation and emission reduction,the green economy and green manufacturing are actively carried out,energy recovery technology and devices are being paid more and more attention.Hydraulic turbine is an energy recovery device.High pressure liquid can do work through hydraulic turbine.It can transform pressure into hydraulic turbine's mechanical energy,do work for other machines,and even further transform into electric energy,so as to reduce production cost and achieve energy saving and emission reduction purposes.In hydraulic turbine device,centrifugal pump reversing hydraulic turbine is widely applied,but there are also some problems such as unstable operation,low efficiency and insufficient structural strength.At present,the research of centrifugal pump reversing hydraulic turbine almost concentrates on single stage single suction centrifugal pump reverse turbine,but there are few studies on guide vane centrifugal pump and multi stage centrifugal pump reversing hydraulic turbine.Moreover,for the impeller of hydraulic turbine,the design method of centrifugal pump impeller is still used at present stage.In recent years,special turbine impeller has begun to appear slowly.There are few people to study the new forward bending impeller.In this paper,the guide vane turbine is chosen as the research object,and the optimal design of the guide vane and the forward curved impeller is carried out,and the numerical simulation is carried out to explore the influence of the hydraulic structure of the guide vane and impeller on the performance of the guide vane hydraulic turbine.The research object is obtained by the model design of the single stage pilot leaf desalination pump by the similarity conversion and velocity coefficient method.(1)The number of vane of guide vane hydraulic turbine is studied.3 kinds of hydraulic turbine models with different guide vanes are designed,and its steady numerical simulation and unsteady numerical simulation are carried out.(2)A new type of front curved blade is studied.Based on the traditional centrifugal pump impeller,the flow volume of the forward curved vane hydraulic turbine is estimated and the main parameters of the forward curved blade are calculated with this flow.In the range of certain parameters of blades,the bowed blades with different number of blades,inlet angles,outlet angles and wrap angles of blades are designed,and numerical simulation is carried out respectively.(3)A comparative analysis is made between the backward curved blade and the forward curved blade.The steady numerical simulation and unsteady numerical simulation of the two hydraulic turbine models under impeller are carried out.Analysis of numerical results of hydraulic turbine under different guide vane number.The results show that under the same water head,the turbine efficiency and maximum recovery power of 7 guide blade number turbine are the largest.Under the same flow rate,the minimum pressure pulsation amplitude of the turbine with 11 guide blade number is minimum.Through the analysis of the numerical results of the front curved blade hydraulic turbine,the results show that the number of blades has the greatest influence on the performance of hydraulic turbine.The change of inlet angle is more likely to cause the deviation of optimal operation point of turbine,and the best turbine performance efficiency is 76.49%.Comparison and analysis of the rear curved blade and the front curved blade,the results show that the front bend blade is more suitable for the operating conditions under the high lift.The optimal efficiency of forward blade hydraulic turbine is slightly greater than the curved blade turbine.In the forward curved vane turbine,the guide vane becomes the largest hydraulic loss component.The pressure pulsation of the forward curved vane hydraulic turbine is larger than that of the rear curved vane turbine.