旋转机械多机组轴系同步运行稳定性研究

发布时间：2018-03-29 23:25

本文选题：多机组轴系　切入点：有限单元法　出处：《东北大学》2012年硕士论文

【摘要】：我国空分装备的生产从20世纪50年代的30m3/h小型设备到现在110000m3/h的超大型空分设备,正在朝特大型化发展。调研国内空分装备发展现状发现,国产大型空分机组运行可靠性差,故障频发,连续运行周期是国外设备的1/2-2/3,停机损失严重,重特大事故时有发生。因此,研究旋转机械多机组轴系同步运行稳定性对空分装备的稳定、安全运行有着非常重要的意义。本文的研究对象为某大型压缩机,研究其低压端由大齿轮、汽轮机、中压缸转子、低压缸转子组成的四跨轴系的同步运行稳定性。多机组轴系各机组在安装前均进行了单机动平衡,但组装以后仍出现振动超标的问题。本文对多跨轴系建立动力学模型,在ANSYS软件环境下进行模态、谐响应分析,研究其运行稳定性,并进一步运用ANSYS软件编程对多轴系系统的固有频率和振动量进行优化,最后运用MATLAB软件计算了轴系系统的标高,进行了以下工作： (1)采用有限单元法对轴系系统进行单元节点的划分,运用APDL语言在ANSYS软件中建立了旋转机械多机组轴系系统的动力学模型； (2)在建立好的模型基础上,进一步利用ANSYS软件对旋转机械多机组轴系这个转子系统进行动力学特性分析,包括了模态分析和谐响应分析,其中模态分析分别考虑了弯曲振动和扭转振动,求得系统前20阶固有频率、临界转速及振型,分析了系统在工作转速下的运行稳定性；利用谐响应分析分析了在工作转速下,不平衡量对整个轴系系统的影响,其中汽轮机轴端的不平衡量对整个轴系影响最大； (3)在前面章节对该轴系建立的动力学模型、进行动力学特性分析的基础上,利用ANSYS软件APDL语言编程对整个多机组轴系系统进行了动态优化设计,分别采用了零阶方法和一阶方法对转子系统固有频率及总振动量这两个目标进行了优化,并比较两种优化方法对不同优化目标的优缺点,且得到了较好的优化结果； (4)考虑轴系中每根转子在重力的作用下会弯曲,轴系标高变化对轴承载荷分配产生影响,为了保证机组运转平稳,转子相联后转动中心必须形成一条光滑的曲线(挠度曲线),各轴承所承受的载荷符合设计要求,本文采用MATMAB软件编程计算确定各轴承标高,得到了轴系挠度曲线和实际的支承反力,为今后的工作打下基础。
[Abstract]:The production of air separation equipment in China is developing from the 30m3/h small equipment in the 1950s to the super large air separation equipment in 110000m3/h now. After investigating the present development situation of domestic air separation equipment, it is found that the operational reliability of domestic large air separation units is poor. The failure frequency and continuous operation period are 1 / 2 / 2 / 3 of the foreign equipment, the downtime loss is serious, and serious and serious accidents occur. Therefore, the study on the stability of the synchronous operation of multi-unit shafting of rotating machinery to the stability of the air separation equipment, Safe operation is of great significance. The research object of this paper is a large compressor. The low pressure end of the compressor is made up of big gear, steam turbine, medium pressure cylinder rotor. The stability of four span shafting system composed of low pressure cylinder rotors. The single machine dynamic balance is carried out for each unit of multi-unit shafting before installation, but the vibration exceeds the standard after assembling. The dynamic model of multi-span shafting is established in this paper. Modal and harmonic response analysis are carried out under the ANSYS software environment. The stability of the system is studied, and the natural frequency and vibration of the multi-shafting system are optimized by using ANSYS software. Finally, the elevation of the shafting system is calculated by using MATLAB software. The following were carried out:. 1) using the finite element method to divide the unit nodes of the shafting system, and using APDL language to establish the dynamic model of the shafting system in the ANSYS software. 2) on the basis of the established model, the dynamic characteristics of the rotor system of multi-unit rotor system of rotating machinery are analyzed by using ANSYS software, including modal analysis and harmonic response analysis. The modal analysis considers the bending vibration and the torsional vibration respectively, obtains the first 20 natural frequency, critical speed and mode shape of the system, analyzes the stability of the system under the working speed, and analyzes the operating speed under the working speed by using the harmonic response analysis. The influence of the unbalance on the whole shafting system, in which the unbalance at the shaft end of the steam turbine has the greatest influence on the whole shafting system; 3) based on the analysis of the dynamic characteristics of the shafting model established in the previous chapter, the dynamic optimization design of the whole shafting system of multi-unit is carried out by using the ANSYS software APDL programming language. The zero order method and the first order method are used to optimize the natural frequency and the total vibration of the rotor system, and the advantages and disadvantages of the two optimization methods for different optimization objectives are compared, and the better optimization results are obtained. (4) considering the bending of each rotor in the shafting under the action of gravity, the change of the elevation of the shafting has an effect on the load distribution of the bearing, in order to ensure the smooth operation of the unit, The rotation center of the rotor must form a smooth curve (deflection curve). The load of each bearing meets the design requirements. This paper uses MATMAB software to calculate and determine the elevation of each bearing. The deflection curve of shaft system and the actual supporting reaction force are obtained, which will lay the foundation for future work.
【学位授予单位】：东北大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH17

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