U型节流阀内部流场与热变形研究

发布时间：2018-05-03 13:28

本文选题：U型节流阀 + 数值计算　；参考：《中国矿业大学》2017年硕士论文

【摘要】：液压U型节流阀是液压系统中重要的控制元件,也是易产生能耗的主要元件,其控制性能直接影响着整个系统的控制精度。由于阀口的节流作用产生的粘性加热效应会导致阀芯与阀体受热膨胀造成阀芯卡紧、卡死等现象,本文采用了理论分析、数值模拟和实验研究相结合的方法,分别对不同阀口开度、不同背压和不同槽口深度情况下阀内油液流场流动特性与阀芯阀体受热变形结果进行了深入研究。(1)分析了油液温升的主要原因,讨论了节流阀内部热传导方式及固体热膨胀机理。基于流体力学、热力学与材料力学基本定律,建立了流场与热分析的理论模型。(2)针对节流阀流场特性及粘性加热导致的温升现象,采用CFD技术建立了节流阀的流场仿真模型,研究得出了不同阀口开度、不同出口压力以及不同节流槽口深度时流体域压力场、速度场、油液温度场的分布情况,并通过理论和实验对比分析了阀口油液流量特性和流场特性。研究结果表明:节流槽是压降的主要区域,节流口出口处形成了高速射流。节流槽口与高速射流冲击的阀体壁面处是高温区域。仿真得到的阀口流量与实验结果一致,高速射流产生区域与实验结果吻合良好。(3)建立了U型节流阀三维稳态热分析模型与结构分析数值模型。对阀芯与阀体进行相应的热传导分析,得出阀芯、阀体的温度分布情况,并讨论了阀口开度、背压值与槽口深度对阀芯阀体温度分布的影响规律。研究结果表明:阀芯左端温度高于右端,且局部高温区域位于节流槽结构轮廓线处;阀体高温区主要存在于阀芯与阀体配合的通孔处和受高速油液冲击的壁面处,阀体上下两方温度分布不一致,下方高温区域面积较大。对阀芯与阀体受热引起的结构变形进行了分析,得到不同开度、不同背压值和槽口深度时的阀芯与阀体热变形趋势。研究结果表明:阀芯整体受热膨胀且阀芯左端形变量大于右侧,节流槽处为主要变形区域;槽口入口处壁面变形方向沿轴向方向,而槽口出口的半圆壁面则主要沿径向方向膨胀;阀体变形区域主要为阀体与阀芯配合的通孔处,尤其是靠近节流口出口阀体壁面发生了径向变形,阀体向内侧膨胀。本文对U型节流阀内部流场及热变形开展了研究,对液压阀的设计与应用提供了一定的参考价值。
[Abstract]:Hydraulic U-type throttle valve is an important control element in hydraulic system, and it is also the main component that can easily produce energy consumption. Its control performance directly affects the control accuracy of the whole system. The viscous heating effect caused by throttling of valve orifice will lead to the valve core and valve body being heated to expand and cause the valve core to be clamped and jammed. In this paper, the method of theoretical analysis, numerical simulation and experimental study is adopted, which combines the theoretical analysis, numerical simulation and experimental research. The main reasons of oil temperature rise are analyzed in the condition of different opening degree of valve, different back pressure and different depth of groove. The internal heat conduction mode and solid thermal expansion mechanism of throttle valve are discussed. Based on the basic laws of fluid mechanics, thermodynamics and material mechanics, a theoretical model of flow field and thermal analysis is established. Aiming at the characteristics of throttle valve flow field and temperature rise caused by viscous heating, the flow field simulation model of throttle valve is established by CFD technology. The distribution of fluid pressure field, velocity field and oil temperature field in different orifice opening, outlet pressure and throttle depth are obtained. Through theoretical and experimental comparison, the flow characteristics and flow field characteristics of the valve are analyzed. The results show that the throttle is the main area of pressure drop and a high speed jet is formed at the outlet of throttle. The high temperature area between the throttled groove and the high-speed jet impingement valve body wall. The simulated valve flow rate is consistent with the experimental results, and the high speed jet generation region is in good agreement with the experimental results.) the three-dimensional steady-state thermal analysis model and the structural analysis numerical model of U-type throttle valve are established. The temperature distribution of the spool and valve body is obtained through the analysis of the corresponding heat conduction between the spool and the valve body, and the influence of valve opening, back pressure value and groove depth on the temperature distribution of the valve core body is discussed. The results show that the temperature at the left end of the valve core is higher than that at the right end, and the local high temperature area is located at the contour of the throttling groove structure, and the high temperature area of the valve body mainly exists in the through hole where the valve core works with the valve body and the wall affected by the high speed oil. The upper and lower sides of the valve body temperature distribution is not consistent, the area of the lower high temperature area is larger. The structural deformation caused by the heating of the spool and the valve body is analyzed, and the hot deformation tendency of the spool and valve body is obtained with different opening, different back pressure and groove depth. The results show that the core is heated and expanded, the left end of the valve core is larger than that of the right side, the main deformation area is at the throttle slot, and the deformation direction of the wall at the entrance of the groove is along the axial direction. The semicircular wall at the outlet of the groove expands mainly along the radial direction, and the deformation area of the valve body is mainly located at the hole where the valve body fits with the valve core, especially the wall surface near the outlet of the throttle outlet has radial deformation, and the valve body expands to the inside. In this paper, the internal flow field and thermal deformation of U-type throttle valve are studied, which provides a certain reference value for the design and application of hydraulic valve.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH137.522

【参考文献】