Hydrodynamic Characteristics Analysis Of High Speed Pump For Turbine

Based on the actual project “ Key Technology Research and Product Development of Seawater Desalination Pump and Energy Recovery Integrated Machine ”,this thesis mainly studies the hydraulic optimization,pressure pulsation and fluid-solid coupling of the turbine side of the seawater desalination turbine energy recovery integrated machine.The research content can provide reference for hydraulic performance optimization and hydrodynamic research of hydraulic turbines.The main contents and conclusions are as follows:(1)The numerical simulation of the original model shows that the hydraulic loss of the impeller domain accounts for 63.99 % of the total hydraulic loss and the efficiency is 78.62 %.That is to say,the design of the impeller will directly affect the turbine efficiency,which is closely related to the complex hydraulic model of the impeller.Under the condition that the size of the impeller has been limited,the orthogonal test method is used to optimize the structure of the original model impeller.The results show that the efficiency of scheme B is improved to86.27 %.The internal flow characteristics before and after optimization are analyzed in detail,and scheme B is verified by experiments.(2)The pressure pulsation phenomenon and its causes in the flow passage components of high speed pump reverse turbine were studied.Firstly,the steady numerical simulation of the turbine is carried out,and the monitoring points are added in the place where the flow pattern is disordered.Then the unsteady numerical simulation of the turbine is carried out for a long time.Finally,the detailed time domain and frequency domain analysis of the flow components are carried out.The results show that the dynamic and static interference between the impeller and the volute causes the pressure fluctuation frequency of each measuring point in the volute to be the blade passing frequency and its frequency doubling,the pressure fluctuation frequency of each measuring point in the impeller domain to be the rotating frequency and its frequency doubling,and the main frequency and secondary frequency of each measuring point in the draft tube domain to be low frequency.(3)The steady-state fluid-solid coupling numerical simulation and transient fluid-solid coupling numerical simulation are carried out on the impeller model of high-speed pump reversal turbine,and the stress and strain of the impeller blade are analyzed.The results show that the stress and strain values of the impeller model under steady-state fluid-solid coupling and transient fluid-solid coupling are not much different and the change rules are similar.Firstly,the equivalent stress gradually decreases with the increase of flow rate and is distributed at the connection between the blade root and the front and rear cover plates.Secondly,the area with large radial deformation is distributed at the blade root and the back cover,and the radial deformation of the former increases with the increase of flow rate,while the radial deformation of the latter is basically the same with the increase of flow rate.In addition,the area with large circumferential deformation is distributed in the middle of the blade root and the blade inlet.The deformation of the former increases with the increase of the flow rate,while the deformation of the latter decreases gradually,and the deformation directions of the former and the latter are opposite.Finally,the total deformation gradually increases with the increase of flow rate,and the area where the total deformation is larger is also transferred,that is,from the back cover plate under the condition of small flow rate to the middle of the blade root under the condition of rated flow rate and large flow rate.