Abstract Auxiliary bearings (AB) support the rotor and protect the magnetic bearing (AMB) system when the AMB is disabled due to power loss or excessive loads. The paper demonstrates that installing a damping device along with the AB can yield extended AB fatigue life, protect the AMB, and reduce vibration, contact force and AB heating. A squeeze film damper (SFD) is an energy dissipation device that has been widely used in the turbo-machinery industry, and as demonstrated in the paper can also work effectively in combination with an AB. Usually, the SFD implements a supply groove to ensure adequate lubricant flow into the film lands. The supply groove can provide significant added mass coefficients and significantly influence the overall impedance of the SFD. Past literature has analyzed the transient response of the rotor dropping onto AB's with squeeze film dampers, none though have considered the influence of the SFD's center groove and its added mass effect on rotor's drop behavior. This paper develops a high fidelity finite element grooved SFD model considering the fluid inertia, and an effective groove clearance is used following the practice appearing in the literature. SFD force coefficients are benchmarked with results of a linear fluid inertia, bulk-flow model developed in the literature, before including them in the rotor – AB system model. The SFD model is integrated into a high fidelity nonlinear auxiliary bearing (angular contact ball bearing) model, which considers the movements, contact force, stress, and temperature of bearing balls, the inner race and outer race. The instantaneous reaction forces from the SFD are calculated with a finite element based solution of Reynold equation at each time step due to the intermittent and large sudden loads. The flexibility of the rotor is included utilizing a Timoshenko beam, finite element model. The fatigue life of the auxiliary bearing when integrated into the SFD is also calculated based on the rain flow counting method. The influence of the added mass of the SFD on the rotor's drop behavior is demonstrated showing that the added mass increases the contact force and peak temperature and reduces the fatigue life of the AB. Therefore, the added mass effect of the SFD should be considered to avoid over predicting the AB fatigue life. The influence of the SFD clearance on the rotor's drop behavior is also studied showing that an optimal clearance exists for increasing the AB fatigue life. Too small of a clearance will yield excessive damping making the effective stiffness too large, and causing high contact forces. Too large of a clearance lowers damping which may lead to a destructive backward whirl. This paper provides key guidelines for auxiliary bearing damper system design.

中文翻译：

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用于磁轴承支撑转子的辅助轴承挤压油膜阻尼器

摘要 辅助轴承 (AB) 支撑转子并在磁轴承 (AMB) 系统因功率损失或负载过大而失效时保护磁轴承 (AMB) 系统。该论文表明，与 AB 一起安装阻尼装置可以延长 AB 疲劳寿命，保护 AMB，并减少振动、接触力和 AB 发热。挤压油膜阻尼器（SFD）是一种在涡轮机械行业中得到广泛应用的能量耗散装置，如论文中所展示的，与 AB 结合也可以有效工作。通常，SFD 会设置一个供应槽，以确保有足够的润滑剂流入油膜平台。电源槽可以提供显着的附加质量系数，并显着影响 SFD 的整体阻抗。过去的文献分析了转子落到 AB' 上的瞬态响应 s 与挤压油膜阻尼器，虽然没有考虑 SFD 的中心凹槽的影响及其对转子下落行为的附加质量效应。本文开发了一种考虑流体惯性的高保真有限元凹槽 SFD 模型，并按照文献中出现的实践使用了有效凹槽间隙。在将 SFD 力系数包含在转子 - AB 系统模型中之前，以文献中开发的线性流体惯性、整体流动模型的结果为基准。SFD模型被集成到一个高保真非线性辅助轴承（角接触球轴承）模型中，该模型考虑了轴承球、内圈和外圈的运动、接触力、应力和温度。由于间歇性和大的突然载荷，SFD 的瞬时反作用力在每个时间步使用雷诺方程的有限元解计算。利用 Timoshenko 梁，有限元模型包括转子的灵活性。辅助轴承在集成到 SFD 时的疲劳寿命也是基于雨流计数法计算的。证明了增加的 SFD 质量对转子下落行为的影响，表明增加的质量增加了接触力和峰值温度，并降低了 AB 的疲劳寿命。因此，应考虑 SFD 的附加质量效应，以避免过度预测 AB 疲劳寿命。SFD间隙对转子的影响' 还研究了跌落行为，表明存在用于增加 AB 疲劳寿命的最佳间隙。间隙太小会产生过度阻尼，使有效刚度太大，并导致高接触力。过大的间隙会降低阻尼，这可能会导致破坏性的反向旋转。本文提供了辅助轴承阻尼系统设计的关键指南。