Study On The Transient Sealing And Dynamic Characteristics Of High Temperature Quick Closing Axial Flow Check Valve

Axial-flow check valve is used in nuclear power,petrochemical and metallurgical industries.It is one of the important equipment to cut off the medium in the system in case of emergency and protect power equipment and installations.Under the actual working condition,the axial-flow check valve not only bears the medium pressure and temperature load,but bears the impact load caused by the fast closing.The opening and closing process of quick closing valve is a dynamic process.The surface pressure and speed of the valve disc directly affect the magnitude of the impact load.In this paper,the dynamic characteristics of the valve disc is analyzed and the impact load is determined by numerical simulation.The axial-flow check valve is taken as the research object to study the strength and sealing failure of the valve when it is subjected to medium pressure,transient temperature load and transient impact load.The main research contents are as follows:1.To understand the development status of check valve by reading the literature at home and abroad.Based on the Hertz theory and Newton’s motion theorem,the paper puts the method to analyze the seal and impact of the axial flow check valve.On the basis of this method,the nonlinear contact of the seal is considered to analyze the force in the process of closing the fast closing check valve.2.The multi field coupling method is used to analyze the steady-state and transient state of the axial flow check valve based on ANSYS.The steady-state analysis shows that the sealing performance under both normal temperature and high temperature conditions is reliable.The sealing performance and structural strength of the axial-flow check valve under different heating rates is further compared by the transient thermal-solid coupling analysis.The results show that different heating rate has a great influence on the sealing performance and structural strength of the check valve.The faster the heating rate is,the greater the thermal impact on the structure made and the greater the structural damage caused.3.Using UDF technology and user-defined function,three dimensional dynamic simulation of the axial flow check valve is carried out by embedding fluent,and the pressure,velocity and turbulent kinetic energy distribution cloud chart of the internal flow field of the check valve at different times are obtained.Besides,the velocity,acceleration and force of the valve disc at different times during the closing process are accurately obtained,and the impact load of the final valve disc hitting the valve seat is obtained.4.Based on the method of display dynamics,LS-DYNA technology is used to study the dynamic response process of the valve impacting during the closing process of the axial flow check valve.The distribution law of the stress and strain of the valve disc and valve seat atdifferent times are obtained.The influence of impact speed on the sealing surface of disc and seat is carried out.It is found that reducing the impact speed of valve disc is the best way to improve the sealing performance and service life of the valve.