Study On The Transient Flow Characteristics Of The Highpressure Hydrogen Gas In Check Valve During The Opening Process

The check valve is one of the critical components in the high-pressure hydrogen systems.During the opening process,the check valve is instantly impacted by the highpressure hydrogen flow,which makes the valve spool produce both a greater acceleration and velocity,and finally collides with the valve seat strongly.The strong impact may cause seal failure and damage to the valves,which seriously threatens both hydrogen refueling stations’ safety and reliability and on-board hydrogen storage systems.Therefore,this article focuses on the opening process of the check valve.Combined with the dynamic mesh and UDF technology,both the internal flow properties and the spool movement characteristics during the opening of the check valve are studied.The effect of filling conditions,spring parameters and spool shape on the check valve’s transient flow characteristics are analyzed,and the mechanism of fluid force change is investigated.The specific research contents of this paper are as follows:Firstly,a computational fluid dynamics(CFD)model for the high-pressure hydrogen flow in the check valves is established and validated.The internal pressure and velocity distributions at different time are studied,and the spool surface pressure change law is concerned.The spool velocity,acceleration,fluid force and kinetic energy changes with the spool stroke are investigated.Concurrently,under different inlet and outlet pressure conditions,the characteristics of the spool’s fluid force and velocity during the movement process are researched,and the impact effect between the spool and the stopper under different working conditions is quantified.Secondly,under specific working conditions,the effect of both spring stiffness coefficient and spring preload on check valve’s opening process is studied separately.The influence of the flow parameters on the hydrogen-flow properties and the spool movement was investigated,and the characteristics of the fluid force on the valve spool surface is obtained.The results show that by increasing the spring stiffness coefficient and reducing the spring preload,the acceleration,speed and kinetic energy of the valve spool during movement will be reduced.Finally,by changing the angle of the spool head and the flow area of the spool through hole,the effect of the spool shape on the transient flow characteristics of the check valve during the opening process is discussed.The simulation results show that the flow sectional areas has a great influence on the fluid force of the spool.Reducing the angle of the spool head and increasing the flow area of through hole can reduce the fluid force of the valve spool.Therefore,the impact by high-pressure hydrogen on the check valve will be decreased.This study will provide research accumulation and technical support for the safety design of high-pressure check valves in the future.