海水淡化高压泵磁液双悬浮轴承多物理场耦合支承机理

Seawater Lubricated Hydrostatic Bearing is the support unit and key component of SWRO Desalination Pump, and it can affect load power and maintenance cycle of SWRO Desalination Pump. Due to low viscosity and special physical-chemical property of the seawater, the bearing capacity and film stiffness of the lubricated film of the seawater lubricated hydrostatic bearing is very low, and then it have been one of the key problems that restricts operation stability and service life of SWRO Desalination Engineering..In order to solve the above problem, the project intends to introduce electromagnetic suspension theory into Seawater Lubricated Hydrostatic Bearing System. Magnetic-Fluid Double Suspension Bearing System for SWRO Desalination Pump is conceived. It includes the follow scientific problems. ① The Heat-Solid-Fluid coupled relationship of magnetic pole / bearing cavity is revealed, and then Magnetic-Fluid coupled supporting mechanism and behavior rule can be explored. ② The bidirectional Solid-Fluid coupled supporting mechanism between magnetic pole / bearing cavity and rotation axis can be explored, and then the multi-constrained statically determinate kinetic model of Magnetic-Fluid Double Suspension Bearing System is established. ③ The coupled relationship between the control channel of each DOF motion and the decoupled control strategy can be explored, and the Multi-DOF decoupled dynamics model is established. The inherent action rule between each bearing performance indicator is revealed, and then the Multi-DOF coupled supporting characteristic library of Magnetic-Fluid Double Suspension Bearing System can be established.The research work can enrich the design theory of Seawater Lubricated Hydrostatic Bearing System and provides the theoretical supports for the improvement of the operating performance and service life of SWRO Desalination Pump.

海水润滑滑动轴承是海水淡化高压泵的核心部件，直接影响负荷功率及转子动力学特性。而由于海水的低粘度及特殊理化性能，使得海水润滑滑动轴承的水膜承载能力及刚度较差，成为制约海水淡化高压泵运行稳定性及服役寿命的关键问题。基于此，本课题将电磁悬浮理论引入到海水润滑滑动轴承中，构思出一种适用于海水淡化高压泵的磁液双悬浮轴承系统，拟解决以下科学问题：①揭示磁极/支承腔的热固液多物理场耦合关系，探索多物理场作用下的磁极/支承腔磁液耦合支承机理及行为规律；②探究磁极/支承腔与转轴之间的双向液固耦合变形规律，建立轴承系统多约束耦合动力学静定化模型；③探求各自由度方向控制通道间耦合关系及解耦控制策略，建立多自由度解耦动力学数学模型；揭示各自由度承载特性的内在作用规律，构建磁液双悬浮轴承系统的多自由度支承特征库。本课题研究可丰富海水润滑滑动轴承的支承理论，为提高海水淡化高压泵的运行稳定性及服役寿命奠定基础。

本课题将电磁悬浮理论引入到海水润滑滑动轴承中，构思出一种适用于海水淡化高压泵的磁液双悬浮轴承系统。课题主要①推导了磁液双悬浮系统的支承单元耦合承载力数学模型；分析了磁液双悬浮系统各支承单元承载力之间耦合关系；分析了液膜厚度对磁液双悬浮轴承系统的静态、动态及振动特性的影响，研究表明随着液膜厚度的增大，所研究的磁液双悬浮系统的承载能力、静刚度、动刚度、固有频率随之减小；②通过一阶轨迹灵敏度法得到支承腔供给流量q和电磁线圈供给电流i为轴承系统的主要影响参数；③研究了磁液双悬浮轴承系统的静态分岔行为和Hopf分岔行为，研究表明：比例反馈系数Kp、线圈电流i0、支承腔流量q0、油膜厚度h0和镀锌层厚度l都会对系统的静态分岔行为产生影响；当线圈电流i0和油膜厚度h0大于某一临界值时零奇点由稳定变为不稳定，系统发生超临界Hopf分岔现象；④采用对角阵解耦方法以及类前馈解耦方法设计出的相应的解耦器；⑤建立了轴承CFD模型，对其进行了多物理场耦合求解，研究表明：轴承内流场压力呈对称分布，进油压力与流量呈线性关系；轴承温度场呈中心对称分布，温升主要集中于线圈及磁极部位；磁液双悬浮轴承的流体冷却率可达98.65%；⑥分析了运行参数和结构参数对磁液双悬浮轴承温升及热变形的影响，研究表明：随着输入电流增加，轴承温度由内向外逐渐增高；随着进油压力的增加，轴承温度由内向外逐渐降低；随着转速提高，液体的摩擦作用致使油膜温度逐渐升高，油膜平均温度与转速近似呈线性比例关系；随着线圈匝数增加，轴承温度及定子热变形近似呈线性增加；随着线圈直径的增加，轴承整体温度以及定子热变形迅速下降；⑦建立了PIV流场观测实验，得到了仿真与试验所得的矢量图与流量—压力曲线图，研究发现：轴承内部流场运动轨迹与仿真结果几乎一致，误差在合理范围内。本课题研究可丰富海水润滑滑动轴承的支承理论，为提高海水淡化高压泵的运行稳定性及服役寿命奠定基础。