伞式轴流式机组下机架动力学特性分析
钱巨林1，张斌1，肖惠民*,2,3，于昊楠2,3，肖志怀2,3
（1.国网新源水电有限公司富春江水力发电厂，浙江 桐庐 311504；2. 武汉大学 动力与机械学院，湖北 武汉 430072；3.水力机械过渡过程教育部重点实验室，湖北 武汉 430072）
摘要：水轮发电机组下机架为承重机架，对机组调心及稳定起着至关重要的作用。建立了某伞式轴流机组下机架的动力学分析模型，利用有限元方法依次计算分析了下机架的挠度、固有频率、振型和谐波响应等动力学特性。下机架最大轴向挠度计算值为1.115 mm，与顶转子试验测得的下机架挠度值接近，说明所建立的模型和采用的计算方法是可靠的。最大轴向挠度值表明下机架变形在安全范围内，刚强度有较大的安全裕量。计算了下机架的前六阶固有频率，分析表明固有频率与引起下机架振动的低阶频率（转频）及叶片通过频率不相重叠，机组正常运行时下机架是安全的。谐波响应分析显示激励频率为17 Hz、41 Hz时，下机架振动的幅值显著增大，与模态分析结果相一致。
关键词：下机架；动力学特性；挠度；模态；谐波响应
中图分类号：TK733+.3 文献标志码：A doi：10.3969/j.issn.1006-0316.2021.09.002
文章编号：1006-0316 (2021) 09-0008-05
Dynamic Characteristics Analysis of the Lower Bracket of Umbrella Axial Flow Unit
QIAN Julin1，ZHANG Bin1，XIAO Huimin2,3， YU Haonan2,3，XIAO Zhihuai2,3
( 1.Fuchunjiang Hydropower Plant of State Grid Xinyuan Co., Ltd., Tonglu 311504, China; 2.School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China; 3.Key Laboratory of Hydraulic Machinery Transients, Ministry of Education, Wuhan 430072, China )
Abstract：The hydro-generator lower bracket is a support frame, which plays a vital role in the centering and stabilization of the unit. In this paper, a dynamic analysis model of the lower bracket of an umbrella axial flow unit is established, and the finite element method is used to calculate and analyze the dynamic characteristics including the deflection, natural frequency, mode shape and harmonic response. The maximum axial deflection of the lower bracket is calculated to be 1.115 mm, which is close to the deflection of the lower bracket measured by the lifting rotor test, which verifies the reliability of the established model and the calculation method. And it indicates that the deformation of the lower bracket is within a safe range, and the stiffness has a large safety margin. The first six order natural frequency of the lower bracket are calculated, and the analysis shows that the natural frequency does not overlap with the lower order frequency (rotating frequency) or the blade passing frequency that causes the vibration of the lower bracket, and the bracket is safe when the unit is running normally. The harmonic response analysis shows that when the excitation frequency is 17 Hz or 41 Hz, the amplitude of lower frame vibration increases significantly, which is consistent with the result of the modal analysis.
Key words：lower bracket；dynamic characteristics；deflection；mode shape；harmonic response
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收稿日期：2021-01-14
基金项目：国家自然科学基金：复杂多变网构下水电机组稳定性机理与机网协调控制研究（51979204）；国网新源水电有限公司富春江水力发电厂项目：国网新源水电富春江电厂水轮发电机组稳定性测试与及转子动力学分析研究（SGTYHT/19-JS-217）
作者简介：钱巨林（1967－），男，浙江诸暨人，高级工程师，主要从事水轮发电机组运行、管理方面的工作，E-mail：julin-qian@sgxy.sgcc.com.cn。*通讯作者：肖惠民（1973－），男，湖南永州人，博士，讲师，主要研究方向为水电机组建模、故障诊断与优化控制等，E-mail：xhm@whu.edu.cn。
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