基于ANSYS硬密封球阀的流固耦合分析及实验研究

发布时间：2018-02-12 18:19

本文关键词： 流场分析实验研究流固耦合应力　出处：《兰州理工大学》2016年硕士论文　论文类型：学位论文

【摘要】：球阀在管路系统中主要用来分配、切断和改变介质流动方向。球阀的结构比较简单,密封性较好,同样的公称尺寸的阀类,球阀所占的体积较小,质量较轻和材料消耗较少。球阀由于低扭矩、轻重量和大流量的特点,近几年来发展特别迅速。广泛应用于电力、石油、煤化工、航天、航空、交通运输、城建、天然气输送管线、海洋石油、核工业、农业以及人们的日常生活。阀门的流体计算是确定阀门水利特性有关参数的过程,所以对阀门的流场进行研究显得至关重要。当介质流过阀门内部时,对于密封面的影响,除了必须的弹簧力之外,同时介质力对密封面有着不可忽略的作用。仅仅依靠实验数据、理论结果和经验总结作为设计阀门的依据,就会在一定程度上造成误差,所以本文采用数值模拟和实验相结合的方法,选取应用普遍的硬密封球阀进行了流场分析和流固耦合分析。本文的主要研究内容和结论如下:1)理论上分析了硬密封球阀的工作原理和流动特性,设计和计算了球体、阀杆、阀体、下盖和阀座的尺寸以及密封面宽度、密封面大小圆直径、密封必需比压以及预紧力,为后续数值模拟奠定基础。2)分析了计算流体力学的求解过程;建立球阀三维模型和划分网格;用FLUENT软件对球阀的几个代表性的开度(20°、30°、40°、50°、60°、70°、80°,对应的相对开度为22%、33%、44%、56%、67%、78%、89%)进行数值模拟。通过速度分布图、压力分布图和速度矢量图研究球阀的流动特性并用实验验证其模拟的正确性。结果表明:在整个流动过程中,流体的最大速度位于球阀的进出口处,此处也为流体冲蚀作用最为严重的区域。随着开启角度的增大,球阀进出口压降减小,流体流动变得平缓,减小了能量损失和对阀的冲蚀作用。在开度小于40°时,流量系数随球阀开度的增大缓慢增加;而在开度大于40°之后,流量系数随球阀开度的增大迅速增加;在球阀开度小于40°时,流阻系数随球阀开度的增大迅速减小;而在开度大于40°之后,流阻系数随球阀开度的增大基本保持不变。3)用ANSYS软件进行了流固耦合分析,把流场模拟得到的介质力加到球体与流体接触的面上,在阀座上施加和实际工况相同的弹簧力并施加与实际工作情况相近的边界条件进行求解,得到了在介质压力和弹簧力的作用下密封面应力沿阀座径向的分布规律以及最大应力和球阀开度的变化关系。结果表明:应力沿阀座密封面径向成递减的趋势,即靠近密封圈内侧应力最大,在密封圈外侧应力最小。当开度大于40°之后应力随球阀开度的增大基本保持不变,这是因为开度大于40°之后,流体有了较稳定的流动状态,流体对密封面的影响相对减小。
[Abstract]:The ball valve is mainly used to distribute, cut off and change the flow direction of the medium in the pipeline system. The ball valve has a simple structure, good sealing, the same nominal size valve class, the ball valve occupies the smaller volume, Ball valves have developed rapidly in recent years due to their characteristics of low torque, light weight and large flow. They are widely used in power, petroleum, coal and chemical industry, aerospace, aviation, transportation, urban construction, etc. Natural gas pipelines, offshore oil, nuclear industry, agriculture, and people's daily lives. The fluid calculation of valves is the process of determining the parameters related to the hydraulic characteristics of valves, So it is very important to study the flow field of the valve. When the medium flows through the valve, the effect of the sealing surface, in addition to the necessary spring force, At the same time, the force of medium plays an important role in the sealing surface. Relying solely on experimental data, theoretical results and experience summary as the basis for valve design, errors will be caused to a certain extent. So the method of numerical simulation and experiment is used in this paper. The flow field analysis and fluid-solid coupling analysis of hard sealing ball valve are carried out. The main contents and conclusions of this paper are as follows: 1) the working principle and flow characteristics of hard seal ball valve are analyzed theoretically, and the ball and valve stem are designed and calculated. The dimensions of the valve body, lower cover and seat, the width of the sealing surface, the diameter of the sealing surface, the specific pressure of the seal and the pretightening force are required to lay the foundation for further numerical simulation. 2) the solution process of computational fluid dynamics is analyzed. Three dimensional model and mesh division of ball valve were established, and numerical simulation of several representative opening degree of ball valve, including 20 掳/ 30 掳/ 40 掳/ 50 掳/ 50 掳/ 50 掳/ 60 掳/ 60 掳/ 70 掳/ 80 掳/ 80 掳, corresponding relative opening degree = 2233 / 4444 / 56 / 7878 / 8989) was carried out by FLUENT software. The flow characteristics of the ball valve are studied by pressure distribution map and velocity vector diagram. The results show that the maximum velocity of the fluid lies at the inlet and outlet of the ball valve during the whole flow process. As the opening angle increases, the pressure drop at the inlet and outlet of the ball valve decreases, and the fluid flow becomes gentle, reducing the energy loss and eroding the valve. When the opening angle is less than 40 掳, The flow coefficient increases slowly with the opening of the ball valve, but increases rapidly with the opening of the ball valve when the opening degree is greater than 40 掳, and decreases rapidly with the increase of the opening degree of the ball valve when the opening degree of the ball valve is less than 40 掳. When the opening is greater than 40 掳, the flow resistance coefficient remains basically unchanged with the increase of the opening degree of the ball valve. (3) the fluid-solid coupling analysis is carried out with ANSYS software, and the medium force obtained by the flow field simulation is added to the surface where the sphere is in contact with the fluid. Apply the same spring force on the seat to the actual working conditions and apply boundary conditions similar to the actual working conditions to be solved, Under the action of medium pressure and spring force, the distribution of sealing surface stress along the radial direction of the valve seat and the relationship between the maximum stress and the opening of the ball valve are obtained. The results show that the stress decreases along the radial direction of the valve seat seal surface. That is, the stress near the inner side of the sealing ring is the largest, and the stress on the outside of the seal ring is the smallest. When the opening degree is greater than 40 掳, the stress will remain basically unchanged with the increase of the opening degree of the ball valve, because when the opening degree is greater than 40 掳, the fluid has a relatively stable flow state. The effect of fluid on sealing surface is relatively small.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TH134

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