Numerical Simulation And Experimental Study On Cavitation Characteristics Of Valve Plate

Nuclear power regulating valve is a large number of medium transport and control equipment used in nuclear power plants.Under high pressure differential environment,the regulating valve is easy to produce cavitation,and cavitation phenomenon often leads to changes in valve flow characteristics,or even damage the valve and pipeline structure,and thus has a significant impact on the safe operation of the system.Therefore,the effective evaluation and detection of valve cavitation is of great significance for the safe operation of nuclear power system.In order to realize the effective evaluation and detection technology of valve cavitation phenomenon,based on the valve plate as the research object,by adopting the combination of theory,simulation and experimental methods,studying the characteristics of valve plate cavitation and the judgment method of cavitation degree,for subsequent valve cavitation phenomenon of diagnosis technology research provides the theoretical and experimental support.Firstly,based on two phase flow and cavitation model,the simulation model of valve plate flow process was established,the influence of valve plate structure parameters and operating condition parameters on flow rate and cavitation is studied.Then,based on the self-designed experimental bench,D8 and D16 single-hole valve plates were designed to study the influence of pressure,pressure differentials and temperature on the flow process.Finally,the effectiveness of the simulation technique is verified by comparing the experimental data with the simulation data,and combined with the simulation data and the experimental data,the pressure recovery coefficient of the valve plate is calculated,and the flow characteristics of the valve plate are obtained,and on the basis of cavitation coefficient,the expression coefficient of cavitation degree of valve plate is studied to express the intensity of cavitation of the valve plate,and provides theoretical support for the study of effective evaluation and detection of cavitation phenomenon.Through theoretical,Simulation and Experimental study on cavitation characteristics of Valve plate,the main conclusions obtained as follows:(1)Valve plate cavitation mainly includes cavitation at orifice of valve plate and cavitation inside pipe behind valve.With the increase of pressure difference,cavitation occurs in the throttle and then in the pipe behind the valve.Cavitation in the back of the valve is a fast nonlinear process.In a small pressure range,the length of the cavitation pipe behind the valve increases rapidly.(2)The simulation and experimental results show that the pressure recovery coefficient of the valve plate has an important effect on the cavitation resistance of the valve plate.The larger the pressure recovery coefficient is,the greater the allowable working pressure difference is,and the stronger the cavitation resistance is.(3)On the basis of cavitation coefficient,combined with simulation and experimental data,the flow pressure differential characteristic diagram of valve plate is given,which provides data support for subsequent valve cavitation diagnosis.