Study On Formation Mechanism And Suppression Of Unbalanced Torque On Piston Valve Core Bottom

Piston valve core is a typical valve core structure and has been widely used in different valve structures due to its advantages of convenient processing,less cavitation,and small open torque.With the widespread application of piston valve core,its existing problems and deficiencies have gradually manifested.In different valves with piston valve core,the problem of unbalanced torque on the valve core bottom is universal,results in the tendency of the piston valve core to overturn,and even causes valve leakage,valve core stuck and other faults.Therefore,research on the formation mechanism and suppression of unbalanced torque is of great significance for improving the performance of piston valves.Supported by National Natural Science Foundation of China through the No.51805470 and Natural Science Foundation of Zhejiang Province through the No.LY20E050016,this paper focus on the piston valve core and adopts computational fluid dynamics and experiment methods to clarify the formation mechanism of the unbalanced torque on the piston valve core bottom.And a simplified device to measure the unbalanced torque of the core is established.Based on the formation mechanism of the unbalanced torque,the piston valve core with a flexible base is proposed.And the effect of the suppression structure on the unbalanced torque of the core is verified.What’s more,the influence of the bottom curvature and hardness of the flexible base on the unbalanced torque is explored.Finally,the valve core of the boric acid regulating valve in nuclear power plant is optimized based on the piston valve core with flexible base,which effectively alleviates the problem of valve core sticking caused by the unbalanced torque on the core bottom.The main research contents and results are as follows:(1)Focused on the pilot piston globe valve,the numerical calculation model is constructed,and the dynamic characteristics,the flow characteristics and the force characteristics in the steady state are analyzed.And the formation mechanism of the unbalance torque on the piston valve core bottom is explored.Based on the formation mechanism of the unbalanced torque,a simplified model of the pilot piston globe valve is proposed,and the effectiveness of the simplified model is verified.In addition,based on the simplified model,a device for measuring the unbalanced torque on the core is designed,and the accuracy of the numerical simulation results is verified.(2)Focused on the simplified model of the piston valve core with flexible base,the bidirectional fluid-solid coupling method is used to study the deformation of the flexible base.The effectiveness of the flexible base in suppressing the unbalanced torque is verified,and the effect mechanism of the bottom curvature and the hardness of the flexible base on the unbalanced torque is explored.(3)Focused on the boric acid control valve,using the thermo-fluid-solid coupling method to analyze the internal flow field characteristics and the deformation of the structures in the valve,the reason is summarized from the perspective of fluid distribution that the valve core stuck in the control valve.And the structure of the boric acid control valve is optimized based on the piston-type valve core with flexible base,and its effectiveness in relieving the valve core stuck caused by the unbalanced torque on the bottom of the valve core is verified.