Study On The Hydraulic Characteristics Of TFW Pressure Regulating Valve For Hydropower Station

Pressure regulating valve is an indispensable pressure regulating device for long-distance water diversion system of low-middle-head hydropower stations.The type of TFW pressure regulating valve is often used in the project instead of pressure regulating well to decompress the pipeline.During the operation of the hydropower station,it is inevitable that the unit will suffer sudden load rejection.As a result,the pressure in the pipeline will increase.At this time,pressure regulating valve will be used to relieve the pressure in the pipeline.Therefor,the effect of pressure regulation in water diversion system will be determined by the performance of the pressure regulating valve.With the increasing frequency of the pressure regulating valve in hydropower station,the requirements for its use are becoming more and more strict.Therefore,with the help of ANSYS/CFX,ANSYS/Workbench and other software,this paper combines the basic knowledge of fluid dynamics,fluid-structure interaction,and so on to perform internal flow simulation,fluid-solid coupling analysis,and pressure pulsation analysis on the pressure regulating valve.The analysis of hydraulic characteristics of pressure regulating valve not only has important theoretical significance in the understanding of pressure regulating valve,but also has corresponding application value in practical engineering.In this paper,the flow field simulation,fluid-solid coupling analysis and pressure pulsation analysis are carried out for the the type of TFW pressure regulating valve in the water conveyance system of hydropower station.The main research work is as follows:(1)According to the purpose of using pressure regulating valves instead of pressure regulating wells in low and medium head hydraulic power stations,this paper studies the design and calculation method of the TFW pressure regulating valves,and expounds the calculation process of the regulation guarantee for the hydropower station with the regulating valve,the data required and the determination of the adjustment and protection parameters.So,based on the results of the regulation guarantee calculation,we can get the basic parameters of the pressure regulating valve.At the same time,this paper also discusses the structure,working principle and installation,operation and maintenance of the TFW type pressure regulating valve.(2)According to the CAD two-dimensional structure of the TFW600/130 pressure regulating valve,UG,CFD and other softwares are used to build a three-dimensional calculation model of the pressure regulating valve inner flow under 11 degrees of opening in this paper.ANSYS/CFX is then used to make numerical simulation analysis,the pressure and streamline distribution cloud diagram of the valve under the opening of 10 mm / 40 mm / 75 mm / 150 mm,and the distribution law of the flow rate,the maximum pressure,the maximum velocity,the maximum turbulent kinetic energy and the maximum turbulent kinetic energy dissipation rate with the opening degree are obtained.At the same time,given the different inlet pressure conditions,the numerical simulation analysis of the internal flow field of the pressure regulating valve under 11 different opening degrees is carried out,and the distribution law of pressure and streamline of the pressure regulating valve with different opening degree under different inlet pressure is obtained.So do the distribution law of the flow rate,the maximum velocity,the maximum turbulent kinetic energy and the maximum turbulent kinetic energy dissipation rate with the opening of the valve under different inlet pressures.(3)UG software is used to build the solid model of the valve disc of the pressure regulating valve,and coupled with the internal fluid model to form a fluid-structure coupling model.The fluid-solid coupling simulation analysis of flow channel fluid and valve disc in pressure regulating valve is carried out by ANSYS/ Workbench,and the distribution law of stress and deformation of valve disc with opening degree is obtained.At the same time,the variation law of deformation and stress of the valve disc under different inlet pressure and opening degree is obtained,which provides the basis for the installation,maintenance and operation of the pressure regulating valve.(4)The pressure pulsation simulation model of the inner flow channel of the pressure regulating valve under 4 kinds of opening is constructed,and different monitoring points are set up to monitor the pressure pulsation in the inner flow channel of the pressure regulating valve under different open degrees to get the law that the pressure fluctuation of the monitoring point in the pressure regulating valve changes with the time under the 4 kinds of opening.