多级离心泵转子耦合系统动力学特性研究

发布时间：2017-12-28 03:09

本文关键词：多级离心泵转子耦合系统动力学特性研究　出处：《浙江大学》2016年博士论文　论文类型：学位论文

【摘要】：多级离心泵作为常见的流体输送关键装置,广泛运用于石油、化工、钢铁、火力及海水淡化等大型工业领域。现阶段,多级离心泵正朝着高流量、高转速及高扬程方向发展,但与此同时,转子的振动、噪音和稳定性问题也更加凸显,这些问题已成为制约多级离心泵转子系统发展的核心问题,究其原因还是原有的计算模型不完善。实际上,多级离心泵转子系统的振动及稳定性问题归根结底是转子动力学中的流-固耦合问题,多级离心泵内不仅存在转子-轴承耦合问题,也存在转子-密封耦合问题,但目前的多级离心泵转子振动模型并未充分考虑密封口环、轴承、轴向力等多个因素之间的耦合作用,转子模型较为单一,无法满足多级离心泵的高流量、高转速及高扬程下的计算需求。因此,建立更加完善的多级离心泵转子系统耦合振动模型,准确预测转子系统的动力学特性,具有重要的研究价值和工程意义。本文以多级离心泵转子耦合系统为研究对象,分别创建了其横向稳态运动模型、横-轴双向耦合振动瞬态模型及非线性运动模型,并对其相应的动力学特性进行了求解。通过不同工况及参数结构对多级离心泵转子耦合系统的动力学行为展开研究,探寻其优化设计方法。同时,针对研究对象采用相应的试验研究以验证数值计算方法的可行性和准确性。论文的主要内容包括以下四个方面：第一,利用二分法和弦截法联合求解的混合法迭代求解滑动轴承静平衡位置,并采用小参数法求解了滑动轴承动特性系数；基于Hertz点接触理论和EHL理论推导了纯径向载荷下的简化调心球轴承刚度动特性系数求解模型并求解了包含接触刚度和油膜刚度共同作用的综合刚度动特性系数；利用Childs的有限长理论和打靶法求解计算了有限长口环密封动特性系数,并利用试验结果进行了验证；结合拉格朗日方程、有限元法和矩阵运算方法建立了完善的多级离心泵转子-轴承-密封耦合系统横向稳态运动模型。第二,设计并改造了国内首套“湿”转子系统试验台,可测试考虑密封支撑作用下的转子耦合动力学响应,通过优化试验部件结构,拓宽并提高了试验转速范围；对不同口环密封压差和间隙条件下多级转子耦合系统的动力学响应进行测试,处理得到转子系统一阶临界转速,验证了多级离心泵转子-轴承-密封耦合系统横向稳态运动模型的可靠性；研究了不同密封压差、密封间隙和转速对多级转子耦合系统稳态动力学特性和稳定性的影响。第三,结合拉格朗日方程和有限元法创建了包含轴向力作用的多级离心泵转子耦合系统横向运动模型和轴向运动模型,并利用相关文献中的多级离心泵轴系的纵向自由振动临界转速对轴向模型进行了验证；采用矩阵整合方法将独立的横向运动模型和轴向运动模型进行了耦合,建立了多级离心泵转子-轴承-密封耦合系统横-轴双向耦合振动模型；采用隐式的Newmark迭代法自行编写了转子系统横-轴双向耦合振动瞬态响应求解程序；详细研究了不同操作工况和结构参数对多级离心泵转子系统横-轴双向耦合振动瞬态动力学特性的影响。第四,利用经典的Capone非线性轴承油膜力模型和Muszynska非线性密封流体力模型,采用解析法建立了单级离心泵转子耦合系统非线性运动模型并通过自编的四阶Runge-Kutta法进行了求解；在单级转子耦合系统的基础上利用有限元法创建了多级离心泵转子耦合系统的非线性无量纲运动微分方程并对其动力学特性进行了求解分析；重点分析了不同转速、轴向力、轴承长度和密封间隙对多种激励力耦合作用下的多级离心泵转子耦合系统非线性动力学行为的影响。研究结果显示,本文提出的混合法相较于二分法和弦截法具有好的计算速度和求解效率；本文提出的多级离心泵转子耦合系统运动模型计算的一阶临界转速值与试验测量所得结果相比,最大相对误差仅有5.5%,其余相对误差均在5%以内；口环密封两端压差、密封间隙、轴向力、转速、轴承长度等参数均对多级转子耦合系统的动力学特性和稳定性具有重要影响；转子耦合系统蕴含丰富的周期运动、准周期运动和多周期运动等非线性运动形式。本文研究内容与结论可为多级离心泵转子耦合系统的结构设计及动力学响应优化设计提供理论指导和参考依据。
[Abstract]:As a common key device for fluid transport, multistage centrifugal pumps are widely used in large industrial fields, such as oil, chemical, steel, fire and seawater desalination. At this stage, multistage centrifugal pump is a high flow, high speed and high head direction, but at the same time, vibration, noise and stability of the rotor is also more prominent, these problems have become the core problem of restricting the development of rotor system of multistage centrifugal pump, the reason is the calculation model of the original is not perfect. In fact, the vibration and stability of rotor system of multistage centrifugal pump rotor dynamics after all is the fluid solid coupling problem, not only the existence of a rotor bearing coupling problem of multistage centrifugal pump, there are rotor seal coupling problems, but the multistage centrifugal pump rotor vibration the dynamic coupling between the multiple factors model did not take into account the seal ring, bearing and axial force of the rotor model is single, unable to meet the computing needs of the multistage centrifugal pump with high flow, high speed and high lift. Therefore, it is of great research value and engineering significance to establish a more perfect coupled vibration model of multistage centrifugal pump rotor system and accurately predict the dynamic characteristics of the rotor system. Taking the rotor coupling system of multi-stage centrifugal pump as the research object, the lateral steady state motion model, the transverse axial bi-directional coupling vibration transient model and the nonlinear motion model were established respectively, and the corresponding dynamic characteristics were solved. The dynamic behavior of the rotor coupling system of a multistage centrifugal pump is studied by different working conditions and parameter structures, and the optimization design method is explored. At the same time, the feasibility and accuracy of the numerical calculation method are verified by the corresponding experimental research. The main contents of this paper include the following four aspects: first, the mixed iterative method combined with sliding bearing is solved by the dichotomy of secant method and the static balance position, and using the small parameter method is used to solve the dynamic coefficient of sliding bearing; Hertz contact theory and EHL theory derives the simplified self-aligning ball bearing stiffness under pure radial load dynamic coefficient model and solved including the contact stiffness and oil film stiffness of the joint effect of the composite stiffness dynamic coefficients based on a finite length calculation; ring seal dynamic coefficients using the finite length theory and shooting method to solve the Childs, and the result was verified by experiment; combined with Lagrange equation, finite element method and the matrix calculation method is established for multistage centrifugal pump rotor perfect bearing seal coupling system of transverse steady motion model. Second, design and transformation of the domestic first "wet" rotor test rig test, can consider the seal rotor coupling dynamics under the support of the response, by optimizing the component structure, broaden and improve the test speed range; dynamic multi rotor coupling system pressure and clearance of the seal under the condition of different ring response test get the rotor first critical speed of the system, to verify the reliability of coupling system of transverse steady state motion model of multistage centrifugal pump rotor bearing seal; the effects of different sealing pressure, sealing gap and speed of multi rotor system dynamics and stability of the steady state. Third, according to the Lagrange equation and the finite element method to create a lateral motion of multistage centrifugal pump rotor system model and axial motion model including axial force, and the critical speed of longitudinal free vibration of multi-stage centrifugal pump shaft in the relevant literature on the axial model is verified through the integration method; matrix model and axial lateral movement the motion model of independent coupling, established a multistage centrifugal pump rotor bearing seal system of cross - coupled axial coupled vibration model of rotor system is developed; cross - axial coupled vibration to solve the transient response procedure using Newmark implicit iterative method; the influence of parameters of different operating conditions and the structure of multi-stage centrifugal pump the cross axis coupling rotor system vibration dynamic characteristics is studied in detail. Fourth, by using the Capone nonlinear bearing oil film force model and Muszynska nonlinear classical physical model is established to seal flow, single-stage centrifugal pump rotor coupling system of nonlinear motion model and by the four order Runge-Kutta method was solved by analytical method; nonlinear based on single rotor system creates multistage centrifugal pump rotor the system using the finite element method of dimensionless differential equations of motion and its dynamic characteristics were computed and analyzed; analyze the effects of different speed, axial force, bearing length and seal gap on a variety of exciting force coupling for the multistage centrifugal pump rotor system nonlinear dynamic behavior. Research results show that the hybrid method is proposed in this paper compared with the dichotomy of secant method calculation speed and efficiency is good; the first critical speed calculation of multistage centrifugal pump motor rotor coupling system model proposed in this paper is compared with the value obtained from the measurement and test results, the maximum relative error is only 5.5%, the relative error is within 5%; export ring seal pressure difference, clearance, axial force, speed and bearing length of the sealing parameters have an important influence on the stability and dynamics of multi rotor system; rotor coupling system contains rich period of motion, quasi periodic motion and multiple periodic motion of nonlinear motion forms. The content and conclusion of this paper can provide theoretical guidance and reference for the structural design and dynamic response optimization of the rotor coupling system of a multistage centrifugal pump.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TH311

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