Research On Flow Field And Thermal Deformation Of U-throttle Valve

U-throttle valve is an important control component in hydraulic system,and it is also the main energy consumption component.It affects the performance of whole system directly.As a result of the viscous heating effect,the spool and valve body will expanded by heat.and then cause the spool clamping phenomenon.In this paper,the methods of theoretical analysis,numerical simulation and experimental research are combined to research this problem.The flow characteristics of the flow field and the thermal deformation of the valve core were studied under different opening,back pressure and notch depth.(1)The main reasons of oil temperature rise are analyzed,the internal heat conduction and the thermal expansion mechanism are discussed.The theoretical model of flow field and thermal model are established based on the fundamental law.(2)The fluid domain simulation model of throttle valve is established,the distribution of pressure field,velocity field and oil temperature field in fluid domain under different conditions are obtained by using Fluent software.The flow characteristics of the valve orifice was analyzed by theory and experiment method.The results show that the throttling groove is the main area of the pressure drop,and the high velocity jet is formed at the outlet of the orifice.The throttle slot and the high speed jet impact on the valve body wall is a high temperature area.The experimental results agree well with the experimental results,and the results show that the jet region is in good agreement with the experimental data.(3)The steady-state thermal analysis model and structural analysis model of U-throttle valve are established.The heat transfer analysis of the spool and valve body is carried out,and the temperature distribution of the valve core and valve body is obtained.The influence of the opening,back pressure and notch depth on the temperature distribution of the valve is discussed.The results show that: the left valve temperature is higher than the right side,and the local high temperature area is located in the section of the groove structure.The high temperature zone of the valve body mainly exists in the wall surface which impacted by the high-speed oil.The upper and lower temperature distribution of the body is not the same,the lower temperature area is larger than the upper side.The structural deformation caused by heating of spool and valve body is analyzed,and the thermal expansion deformation law of valve core and valve body with different opening,back pressure and notch depth is obtained.The results show that the valve core is heated and expanded,the left side has great deformation than the right side of the spool.The main deformation zone is located in the throttling groove.The deformation direction of the notch entrance is along with the axial direction,and the slot wall is mainly expand along with the radial direction.The main deformation area of the valve body is located the area of axle hole fit,especially near the outlet of orifice where the radial deformation occurs.In this paper,the internal flow field and thermal deformation of U-throttle valve were studied,which provides some reference value for the design and improvement of hydraulic valve.