三支臂弧形钢闸门静动力特性研究

发布时间：2018-08-27 10:18

【摘要】：金属结构对于水利枢纽的正常运行是不可或缺的,而闸门作为泄水通道的控制设施更是重中之重,弧形闸门具有结构轻巧、受力合理、启闭方便、流态良好等诸多优点。弧形闸门是一个复杂的空间体系,支臂的布置方式、孔口尺寸的大小、作用水头的高低都会对其工作特性产生影响,针对特殊体型弧形闸门的静动力特性进行研究是十分必要的。本文以浩口水电站表孔工作闸门这一大尺寸、低水头的三支臂弧形闸门为背景,建立三维有限元模型,通过ANSYS进行静动力分析,研究结构在不同情况下的静力特性以及自振特性,为结构的优化设计和日常安全运行提出合理的意见。本文首先概述了近年来国内外关于弧形闸门设计以及闸门振动的研究进展,简要阐述了有限单元法的基本概念和分析过程,介绍了了本文计算分析所采用的ANSYS软件的特点和基本功能,针对静力分析中主要采用的薄板有限元法以及自振分析中所涉及的模态分析理论进行了重点说明。其次,本文通过浩口三支臂弧形闸门有限元模型,对比分析了闸门关闭与启门瞬时、体型优化前后、两种支臂布置形式这三方面弧门的静力特性。发现启门前后浩口弧门的应力分布未发生明显改变,但是启门瞬时闸门位移从静力挡水时的向下游挠曲变为以绕轴转动为主。针对前期计算分析结果,提出增加弧门裤衩端连接端板厚度优化方案,改善了该部位应力情况。两种支臂体型相比,双支臂结构纵向刚度略弱于三支臂结构,可能会导致支臂上方的门叶向下游挠曲;斜支臂因与门叶有一定的交角,会在支臂与门叶相连接处出现挤压应力。最后,基于原体型可能存在的振动问题,针对薄弱体型进行修改强化,得到了良好的优化效果与结构布置形式,说明该方法可以有效地提高闸门的低阶自振频率并改变其振型。水体附加质量对闸门沿切向的振动影响比较大,并且会整体降低闸门的自振频率。比较不同开度下闸门的自振特性,发现随着开度的增加,弧形闸门与水体接触面积逐渐减小,所受水体附加质量效应的影响也逐渐减小,闸门的自振频率会随之逐渐增大,因此在闸门的日常运行中要尽量避免小开度运行。
[Abstract]:The metal structure is indispensable to the normal operation of the water conservancy project, and the gate as the control facility of the discharge channel is the most important. The radial gate has many advantages, such as light structure, reasonable force, convenient opening and closing, good flow pattern and so on. It is necessary to study the static and dynamic characteristics of arc gates with special body shape. In this paper, a three-dimensional finite element model is established for the large-sized and low-head three-arm arc gate of Haokou Hydropower Station. This paper studies the static and self-vibration characteristics of structures under different conditions, and puts forward reasonable opinions for optimum design and daily safe operation of structures. Firstly, this paper summarizes the research progress of arc gate design and gate vibration at home and abroad in recent years, briefly expounds the basic concepts and analysis process of finite element method, and introduces. The characteristics and basic functions of the ANSYS software used in the calculation and analysis in this paper are described. The thin plate finite element method and the modal analysis theory involved in the natural vibration analysis are emphasized. Secondly, through the finite element model of Haokou three-arm radial gate, the closing and opening moments of the gate are compared and analyzed. It is found that the stress distribution of Haokou radial gate has not changed obviously before and after the gate is opened, but the displacement of the gate changes from downstream deflection to rotation around the axis. Compared with the three-arm structure, the longitudinal stiffness of the double-arm structure is slightly weaker than that of the three-arm structure, which may lead to the downstream deflection of the portal blade above the arm; and the oblique arm will appear the extrusion stress at the junction of the arm and the portal blade because of the angle between the oblique arm and the portal blade. This method can effectively improve the low-order natural frequency and change the mode of vibration of the gate. The additional mass of the water body has a great influence on the tangential vibration of the gate, and will reduce the overall vibration of the gate. Comparing the self-vibration characteristics of the gate under different opening degrees, it is found that the contact area between the radial gate and the water body decreases gradually with the increase of opening degrees, and the influence of the additional mass effect on the water body decreases gradually, and the self-vibration frequency of the gate increases gradually with the increase of opening degrees. Therefore, the small opening operation should be avoided as far as possible in the daily operation of the gate.
【学位授予单位】：武汉大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV663.2

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