Abstract:Combined with the physical and chemical properties of water,the computational fluid dynamics model of the twostage throttle with a movable seat was established.Numerical study was carried out to investigate the flow characteristics including the flow field,the pressure field,cavitation,flowpressure difference relationship and flow induced force.A novel twostage throttle valve with a movable seat was developed,of which the axial force acting on the movable seat was balanced due to the equivalent pressure of the step areas.An umbrellashaped poppet was used to reduce the force acting on the seat due to water shock effectively.At the inlet where the fluid entered the spool through the seat,the structure of the stem in the spool was designed to reduce the impact and erosion of the flow induced force acting on the seat by conducting the force of the ejected fluid through the stem to the spool.The corresponding simulation model was established by Fluent software,and the influence of input pressure,spool angle and valve opening on the dynamic characteristics of the system was simulated.Hydraulic test platform was built to verify the simulation results.The results show that:the pressure at the valve port of the movable seat throttle valve decreases rapidly,the smaller the valve opening,the larger the pressure drop;the pressure drop at the secondstage throttle is large and low,and cavitation is easily occurred;drainage holes,spool angle and twostage throttle can effectively reduce operating differential pressure,flow force,cavitation of the valve and improve the performance and service life of the valve.