Control valves of water storage tank in ultra-supercritical unit boiler is important valves in the power plant system.In order to explore the changing law of interior flow field of the valve

the flow filed model of this valve was established

and analysis was carried out based on the Fluent turbulence model and multiphase flow technology.The results show that

with the design structure and conditions

the fluid is in critical state

serious evaporation will occur when it flows through the gap between the valve stem and seat

which will make the flow field be extremely unsteady.The valve stem angle has a great effect on the flow field

as the angle increases

the fluid velocity decreases gradually and the total evaporation quantity reduces.When two plates are added into the pipe system

the flow field speed is reduced by 19.2% while the total amount of volume fraction is 86.4%

which means the entire flow field becomes uniform.The results have a theoretical guidance to the structural design and optimization of the valve

and also have a positive significance to promote the localization of the valve.