【作者】 杨维；

【导师】 刘延俊； 薛钢；

【作者基本信息】 山东大学 ， 机械工程（专业学位）， 2022， 硕士

【摘要】 全球经济正在飞速发展,各国出现能源紧缺的问题,对能源的需求非常迫切,清洁能源在国民经济发展中扮演着举足轻重的角色,其中以温差能形式存在的储量巨大、清洁无污染的海洋能成为各国专家学者的关注焦点,而透平作为海洋温差能发电系统的核心部件,其对能源的利用率以及系统的发电效率影响重大,本文以海洋温差能发电系统中的双透平发电机组为研究对象,针对气体轴承-转子系统不稳定性问题研究透平机组中静压气体轴承的承载特性以及气浮转子系统的动力学特性,并对双透平发电机组进行实验测试,主要研究内容如下:首先结合纳维-斯托克斯方程、连续性方程以及速度边界条件推导出考虑节流孔流量特性的气体雷诺方程,并推导轴承气膜厚度方程以及节流孔控制区域内流出流量的计算方法;然后,通过有限差分法结合牛顿迭代法将雷诺方程进行离散,构造迭代方程,基于Matlab编制静压径向气体轴承承载特性的求解程序,对轴承间隙中的气膜压力分布状况进行数值模拟,在此基础上研究分析供气压力、气膜厚度、偏心率、长径比、节流孔位置、节流孔直径及数量、气源介质对轴承承载特性的影响规律;随后,利用变分原理构造泛函数,基于有限单元法利用超松弛迭代法和比例分割法对静压止推气体轴承的承载特性进行求解,利用Matlab编写计算程序,对轴承间隙中的气膜压力分布进行数值模拟,研究分析供气压力、节流孔直径、数量以及气源介质对轴承承载性能、气体质量流量的影响规律,并且对上述两种轴承的结构参数和工况条件进行了动态优选,采用的研究方法可为静压气体轴承的优化设计分析提供一定的参考价值。针对50 kW双透平发电机组,利用遗传算法优选气动参数,对透平进行一维气动设计,通过Solidworks进行三维实体建模,借助ANSYS对转子系统进行结构分析,得到转子系统应力应变图,并建立双透平气体轴承-转子系统动力学模型,将气体轴承等效成弹簧单元,采用模态分析法求解系统的临界转速以及模态振型,分析轴承支承刚度、旋转预应力对系统固有频率的影响;然后基于模态分析对转子系统进行谐响应分析,得到叶轮受到外界激振力时转子系统的幅频特性曲线;最后对转子系统进行动平衡实验,调整转子系统不平衡量,并搭建实验平台研究机组在瞬态升降速过程中的振动状况,实验结果表明气体轴承以及机组的稳定性较好,研究结果可为双透平气体轴承-转子系统的动力学分析、优化分析、实验研究提供一定的理论依据和实验依据,具有非常实际的工程应用意义。更多还原

【Abstract】 With the rapid development of global economy,there is a widespread problem of energy shortage in all countries,and the demand for energy is urgent.Clean energy plays a pivotal role in the development of national economy.Among there are huge reserves,clean and pollution-free ocean energy in the form of ocean thermal energy that have become the focus of attention of experts and scholars from all over the world.And as the core of the ocean thermal energy power generation system,the turbine has a significant impact on the utilization rate of energy and the efficiency of the power generation system.In this paper,the dual-turbine generator set in the ocean thermal energy power generation system is taken as the research object.Aiming at the instability of the gas bearing-rotor system,the load-carrying characteristics of the hydrostatic gas bearing in the turbine unit and the dynamic characteristics of the air-floating rotor system are studied,and the experimental test of the double-turbine generator unit is carried out.The main research contents are as follows:Firstly,The hydrostatic gas Reynolds equation considering the flow characteristics of the orifice is deduced by combining the Navier-Stokes equation,the continuity equation and the velocity boundary condition.The solution process of the gas film thickness equation of the gas bearing and the characteristic equation of the orifice flow,and the calculation method of the outflow in the control area of the orifice is given.Then,the Reynolds equation is discretized by the finite difference method and the Newton iteration method,and the characteristics of the hydrostatic radial gas bearing solution program is compiled based on Matlab.The air film pressure distribution is numerically simulated,and on this basis,the influence of gas pressure,gas film thickness,eccentricity,length-diameter ratio,orifice position,orifice diameter and quantity,air source medium on the load-bearing characteristics of bearing are analyzed.Then,the variational principle is used to construct the functional,and the Reynolds equation of the hydrostatic gas thrust bearing is solved by the finite element method,the over-relaxation iterative method and the proportional division method.Matlab calculation program was written to study the numerical simulation of the air film pressure distribution in the bearing clearance,and analyze the influence of air supply pressure,orifice diameter and quantity on bearing performance,and gas mass flow.In addition,the structural parameters and working conditions of the above two bearings are dynamically optimized.The research method can provide reference value for the optimization design and analysis of hydrostatic gas bearings.For a 50 kW dual-turbine generator set,aerodynamic parameters are optimized by genetic algorithm,one-dimensional aerodynamic design of the turbine is carried out,and Solidworks is used for three-dimensional modeling.With the help of ANSYS,the structure of the rotor system is analyzed,and obtain stress-strain diagram of rotor system.The dynamic model of the dual-turbine gas bearing-rotor system is established,and the gas bearing is equivalent to a spring unit.Then modal analysis method is adopted to solve the critical speed,modal shape of the system.The effects of bearing support stiffness and rotational prestress on the natural frequency of the system are analyzed.Then the harmonic response analysis of the rotor system is carried out based on the modal analysis.The amplitude-frequency characteristic curve of rotor system is obtained when the impeller is subjected to external excitation force.Finally,the dynamic balance experiment of the rotor system is carried out to adjust the unbalance of the rotor system,and build an experimental platform to study the vibration of the unit in the transient speed-up and speed-down process.The experimental results show that the stability of gas bearing and unit is good.The research results can provide a theoretical basis and experimental basis for the dynamic analysis,optimization analysis,experimental research of the gas bearing-rotor system,and have very practical engineering application significance.更多还原