浮动环密封-转子系统动力学特性研究
发布时间：2018-10-30 18:32
【摘要】：随着旋转机械向着高速、高效、大跨距、大功率方向的发展，浮动环密封两侧承受的压差增大，使得浮动环密封-转子系统的非线性动力学特性日益凸显。传统的浮动环密封研究中通常采用线性化的小扰动理论进行分析和设计，其不能很好的描述系统的非线性特性，因而具有一定的应用局限性。因此建立浮动环密封的非线性油膜力模型对于浮动环密封-转子系统的非线性动力学特性分析具有重要意义。针对上述问题，本文对浮动环的结构、工作原理及其受力情况进行了研究，建立浮动环密封非线性油膜力近似解析模型，应用该模型对浮动环密封-汽轮机转子系统的非线性动力学特性进行数值仿真，，主要研究内容如下： (1)基于小间隙油膜润滑雷诺方程，采用类似于短轴承模型假设，考虑浮动环两端的压力边界条件和间隙入口的流体Lomakin效应，建立了浮动环非线性油膜力模型，并对浮动环压力分布及浮动环静态特性进行了数值仿真。 (2)建立了浮动环流动的三维模型，在此基础之上对油槽浮动环间隙内的流场进行数值仿真研究，分析了浮动环的中间周向油槽几何尺寸及浮动环两端压差对油槽内的压力分布的影响；数值仿真研究了浮动环偏心率及油槽对浮动环泄漏量的影响规律。研究表明：浮动环的泄漏量随着偏心率的增加而增大，而中间周向油槽能减小浮动环的泄漏量，且在保持油槽的深度或宽度不变时，随着油槽深宽比的增加，浮动环的泄漏量呈逐渐减小的趋势。 (3)基于建立的浮动环油膜力模型的基础之上，结合有限元理论建立了浮动环密封-汽轮机转子系统的动力学模型并对其数值仿真研究，获得不同轴承支承刚度下汽轮机转子的临界转速、模态振型及动力学响应，分析了不同轴承支承刚度下浮动环油膜力对转子临界转速和稳定性的影响。 (4)基于已建立的浮动环密封-转子系统的动力学模型，数值仿真研究了浮动环的结构参数(长径比、间隙比、润滑油粘度、中间周向油槽的几何尺寸)和浮动环两端压差对浮动环密封-转子系统的动力学响应的影响，分析了浮动环密封-转子系统的稳定性随各影响因素的变化规律。研究表明，适当的减小浮动环的长径比、润滑油粘度或增加间隙比、两端压差会提高浮动环密封-汽轮机转子系统的稳定性；在浮动环中间开设周向油槽能较大幅度提高浮动环密封-汽轮机转子系统的稳定性，同时随着油槽宽度的增加，系统的稳定性逐渐提高。
[Abstract]:With the development of rotating machinery in the direction of high speed, high efficiency, long span and high power, the pressure difference between the two sides of the floating ring seal increases, which makes the nonlinear dynamic characteristics of the floating ring seal rotor system more and more prominent. In the traditional research of floating ring seal, the linearized small disturbance theory is usually used to analyze and design, which can not well describe the nonlinear characteristics of the system, so it has certain application limitations. Therefore, the establishment of a nonlinear oil film force model for the floating ring seal is of great significance for the analysis of the nonlinear dynamic characteristics of the floating ring seal rotor system. In view of the above problems, the structure, working principle and stress of the floating ring are studied in this paper, and the approximate analytical model of the nonlinear oil film force of the floating ring seal is established. The nonlinear dynamic characteristics of floating ring seal turbine rotor system are numerically simulated by this model. The main research contents are as follows: (1) based on the Reynolds equation of small clearance oil film lubrication, the assumption similar to that of short bearing model is adopted. Considering the pressure boundary conditions at the two ends of the floating ring and the fluid Lomakin effect at the gap inlet, a nonlinear oil film force model of the floating ring is established, and the pressure distribution of the floating ring and the static characteristics of the floating ring are numerically simulated. (2) the three-dimensional model of floating ring flow is established, and the numerical simulation of the flow field in the gap of the floating ring of the oil tank is carried out on the basis of the model. The influence of the geometry size of the middle circumferential oil tank and the pressure difference between the two ends of the floating ring on the pressure distribution in the oil tank is analyzed. The influence of the eccentricity of the floating ring and the oil tank on the leakage of the floating ring is studied numerically. The results show that the leakage of the floating ring increases with the increase of the eccentricity, and the leakage of the floating ring can be reduced by the middle circumferential oil tank, and when the depth or width of the oil tank is kept constant, the ratio of depth to width of the oil tank increases. The leakage of the floating ring is decreasing gradually. (3) based on the oil film force model of floating ring, the dynamic model of floating ring seal turbine rotor system is established with finite element theory and its numerical simulation is studied. The critical speed modal mode and dynamic response of turbine rotor under different bearing stiffness are obtained. The influence of floating ring oil film force on the critical speed and stability of the rotor under different bearing supporting stiffness is analyzed. (4) based on the established dynamic model of floating ring seal rotor system, the structural parameters (aspect ratio, clearance ratio, lubricating oil viscosity) of floating ring are numerically simulated. The effects of the geometric dimension of the middle circumferential oil groove) and the pressure difference between the two ends of the floating ring on the dynamic response of the floating ring seal rotor system are analyzed. The variation of the stability of the floating ring seal rotor system with the influence factors is analyzed. The results show that the stability of the rotor system of the floating ring can be improved by decreasing the ratio of length to diameter of the floating ring, increasing the viscosity of the lubricating oil or increasing the clearance ratio, and the pressure difference between the two ends will improve the stability of the rotor system of the floating ring. Setting a circumferential oil groove in the middle of the floating ring can greatly improve the stability of the rotor system of the floating ring seal steam turbine. At the same time, the stability of the system increases gradually with the increase of the width of the oil slot.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH133
本文编号：2300822
[Abstract]:With the development of rotating machinery in the direction of high speed, high efficiency, long span and high power, the pressure difference between the two sides of the floating ring seal increases, which makes the nonlinear dynamic characteristics of the floating ring seal rotor system more and more prominent. In the traditional research of floating ring seal, the linearized small disturbance theory is usually used to analyze and design, which can not well describe the nonlinear characteristics of the system, so it has certain application limitations. Therefore, the establishment of a nonlinear oil film force model for the floating ring seal is of great significance for the analysis of the nonlinear dynamic characteristics of the floating ring seal rotor system. In view of the above problems, the structure, working principle and stress of the floating ring are studied in this paper, and the approximate analytical model of the nonlinear oil film force of the floating ring seal is established. The nonlinear dynamic characteristics of floating ring seal turbine rotor system are numerically simulated by this model. The main research contents are as follows: (1) based on the Reynolds equation of small clearance oil film lubrication, the assumption similar to that of short bearing model is adopted. Considering the pressure boundary conditions at the two ends of the floating ring and the fluid Lomakin effect at the gap inlet, a nonlinear oil film force model of the floating ring is established, and the pressure distribution of the floating ring and the static characteristics of the floating ring are numerically simulated. (2) the three-dimensional model of floating ring flow is established, and the numerical simulation of the flow field in the gap of the floating ring of the oil tank is carried out on the basis of the model. The influence of the geometry size of the middle circumferential oil tank and the pressure difference between the two ends of the floating ring on the pressure distribution in the oil tank is analyzed. The influence of the eccentricity of the floating ring and the oil tank on the leakage of the floating ring is studied numerically. The results show that the leakage of the floating ring increases with the increase of the eccentricity, and the leakage of the floating ring can be reduced by the middle circumferential oil tank, and when the depth or width of the oil tank is kept constant, the ratio of depth to width of the oil tank increases. The leakage of the floating ring is decreasing gradually. (3) based on the oil film force model of floating ring, the dynamic model of floating ring seal turbine rotor system is established with finite element theory and its numerical simulation is studied. The critical speed modal mode and dynamic response of turbine rotor under different bearing stiffness are obtained. The influence of floating ring oil film force on the critical speed and stability of the rotor under different bearing supporting stiffness is analyzed. (4) based on the established dynamic model of floating ring seal rotor system, the structural parameters (aspect ratio, clearance ratio, lubricating oil viscosity) of floating ring are numerically simulated. The effects of the geometric dimension of the middle circumferential oil groove) and the pressure difference between the two ends of the floating ring on the dynamic response of the floating ring seal rotor system are analyzed. The variation of the stability of the floating ring seal rotor system with the influence factors is analyzed. The results show that the stability of the rotor system of the floating ring can be improved by decreasing the ratio of length to diameter of the floating ring, increasing the viscosity of the lubricating oil or increasing the clearance ratio, and the pressure difference between the two ends will improve the stability of the rotor system of the floating ring. Setting a circumferential oil groove in the middle of the floating ring can greatly improve the stability of the rotor system of the floating ring seal steam turbine. At the same time, the stability of the system increases gradually with the increase of the width of the oil slot.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH133
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