船用大型低速重载水润滑艉轴承微观界面润滑机理及结构优化设计研究

Large-size, low-speed and heavy-duty marine water lubricated journal stern tube bearing is an important part of the ship's propulsion system. The mechanical properties of the bearing has an important influence on the dynamic response of the rotor system and the acoustic stealth of the ship. So far researches on water lubricated bearings are mainly based on the hydrodynamic lubrication (HL) theory or elasto-hydrodynamic lubrication (EHL) theory. However, due to the particularity in bearing material, structure and lubrication medium, the composite surface roughness of the bearing has the same order of magnitude as the film thickness under the condition of low speed and heavy load, asperities contacts between the journal and bushing surfaces are expected. It will change the fluid flow state of the micro-interface and thus lead to the failure of traditional theoretical analysis methods eventually. Faults frequently occur in engineering application due to the bearing designed according to traditional theory, and will seriously affect the normal service of the ship. Therefore, it is urgent to propose a new theoretical method to guide the design of such bearings. Addressed on the problem mentioned above, in-depth and systematic theoretical and experimental study on the micro-interface modelling method、lubrication states and mechanism on the micro-interface、 dynamic characteristics analysis and optimization of bearing-rotor coupled systems will be conducted in this proposal. Through the investigation, the micro-interface lubrication mechanism will be revealed. A set of theory and method for the optimum design for such bearings will be put forward. The study presented here can provide a solid theoretical support for the design and development of high efficiency and low noise marine water lubricated journal bearing.

大型低速重载水润滑艉轴承作为舰艇推进轴系的重要组成部分，其力学性能对轴系的动力学特性及舰艇的声隐身性有重要影响。目前国内外有关水润滑轴承的研究主要基于流体动力润滑或弹流润滑理论，但在低速重载工况下，因轴承在材料、结构及润滑介质等方面存在的特殊性，其润滑界面的综合表面粗糙度与水膜厚度已在同一数量级，轴颈和衬层表面微凸体在一定条件下将发生直接接触，改变了微观界面润滑状态，导致传统理论分析方法失效，基于传统理论设计的轴承在工程实际应用中故障频发，严重影响了舰船的正常服役，亟待提出新的理论方法指导该类轴承的工程设计。基于此，本课题拟重点就低速重载水润滑轴承微观界面力学建模与分析、轴承微观界面润滑状态与机理、轴承-转子系统耦合动力学特性分析与优化等开展系统深入的理论和试验研究，通过研究揭示水润滑轴承微观界面润滑机理，提出新的水润滑轴承优化设计理论和方法，为高效低噪水润滑轴承的设计提供坚实的理论支撑。

目前国内外有关水润滑轴承的研究主要基于流体动力润滑或弹流润滑理论，但在低速重载工况下，因轴承在材料、结构及润滑介质等方面存在的特殊性，其润滑界面的综合表面粗糙度与水膜厚度已在同一数量级，轴颈和衬层表面微凸体在一定条件下将发生直接接触，改变了微观界面润滑状态，导致传统理论分析方法失效，基于传统理论设计的轴承在工程实际应用中故障频发，严重影响了舰船的正常服役，亟待提出新的理论方法指导该类轴承的工程设计。本课题建立了水润滑轴承微观界面力学建模分析方法及其在轴承微观界面润滑机理分析中的应用，研究了不同工况下水润滑轴承润滑状态的转变及其润滑界面力学性状，阐述了润滑界面特征参数随表面形貌参数变化的演化规律；建立了考虑轴颈倾斜、轴承弹性变形、表面形貌及微凸峰接触的轴承混合润滑分析模型，分析了润滑状态转变的机理；对轴承进行优化设计，提出在轴承轴向两端面设计渐扩形开口结构和轴瓦中加入斜橡胶层结构和加入斜橡胶层的轴承结构，其压力分布不均现象得到显著改善；利用试验平台进行了轴承综合性能试验，获取了液膜压力、轴瓦温度、液膜厚度、摩擦力等实测数据，验证了本文的理论分析模型。通过本研究为低速重载轴承的理论分析和优化设计提供新的途径和方法，具有重要的理论和实际意义。相关研究为我国船用艉轴承的优化设计和承载能力提升提供了新思路；对水润滑轴承的优化设计便于应用于实际轴承的设计。