轴振与非对称流场耦合作用下船舶尾轴承瞬态润滑机理研究

Stern tube bearing is one of the most key components on the deep sea oil platform. It is important for the oil platform to supply power for positioning platform and resisting storm. And it also plays a significant role in bracing stern shaft and propeller. If lubrication of stern tube bearing is broken, contact wear will occur at the contact portion between journal and bearing. The platform cannot work continuously, stably, reliably. Normal sailing and ability to resist storm will be influenced as well. The project presents an entirely new approach to dynamic mesh that is applicable to the calculation of transient flow field at first, and realizes multiple fluid-structure coupling calculation with transient flow field of bearing to control mesh distortion. In the second place, several kinds of nonlinear excitation will be considered to build the motion equations of shaft system. The performance of low viscosity lubricant film with the effects of multiple fluid-structure coupling will also be researched to find out the transient lubricating mechanism of marine stern tube bearing under the influence of the coupling of axis vibration and asymmetrical flow field. At last, by designing a performance test of rotor bearing system and large experiments and theory calculation, the interior relations between transient flow field of stern tube bearing and stability of propeller axis will be shown, the key point of affecting the dynamic behaviors of stern tube bearing could also be found out. This project aims to consummate the engineering design theory of water lubrication bearing, supplies the theoretic support for the study of the navigation of deep sea drilling platform and the dynamic positioning system with self-owned intellectual property rights by our own country.

尾轴承是深海海洋平台定位动力与抗风暴侧推螺旋桨的关键部件，起着支撑尾轴和螺旋桨的作用。尾轴承润滑好坏不仅直接影响其是否可靠稳定工作，而且也间接关系到平台的正常航行与在强风暴下的生存能力。本项目首先提出一种全新的适用于瞬态流场计算的变流域动网格方法，实现多重流固耦合下轴承变流域动网格的网格畸变控制；其次，考虑多种非线性激励力作用建立螺旋桨轴系运动方程，开展热流固多场耦合作用下尾轴承的低粘度介质液膜润滑性能研究，揭示轴振与非对称流场耦合作用下船舶尾轴承的瞬态润滑机理；最后，设计转子-滑动轴承性能试验装置，验证理论预测结果，揭示尾轴承瞬态流场与螺旋桨轴稳定性之间的内在关系，提出影响尾轴承动力特性的关键因素。项目成果旨在完善水润滑轴承的工程设计理论，为我国深度研制具有自主知识产权的深海钻井平台航行与定位动力系统提供理论支撑。

针对尾轴承瞬态润滑流场与动力特性研究的不足，本项目首先提出一种全新的适用于瞬态流场计算的变流域结构动网格方法，该方法在网格更新过程中网格数目和拓扑结构能够保持不变，实现了尾轴承流场的瞬态计算，结果表明：大扰动下尾轴承承载力的非线性效应逐渐增强，且在相同工作条件下，相对于圆柱型水润滑轴承，凹槽型水润滑轴承瞬态承载力的非线性效应更为明显。其次，考虑多种非线性激励力作用建立螺旋桨轴系运动方程，建立了不同润滑介质、轴承结构、工况条件下的尾轴-尾轴承瞬态流固耦合模型，揭示了轴振与非对称流场耦合作用下轴承结构、瞬态流场、尾轴涡动之间的耦合关系，结果表明：多油楔滑动轴承的油膜力可以提供足够的刚度和阻尼，使得尾轴保持较高的稳定性，同时发现适当增加不凝结气体可以提高尾轴稳定裕度，但是会导致静平衡位置下降，引起尾轴涡动幅度增加，增加轴与轴承碰摩的风险。再次，研究了一种适用于水润滑的新型织构型尾轴承，并提出了织构型尾轴承动压叠加承载机理，针对织构型接触副的多参数问题，成功引入了基于流固耦合和响应曲面的多目标优化算法，结果表明：织构的最优高度比都在0.60~0.65范围内，且接触副的弹性变形并不影响该比例。最后，基于动力相似原理设计了转子-滑动轴承性能试验装置，揭示了尾轴承瞬态流场与转子稳定性之间的内在关系，结果表明：椭圆型轴承相较于传统的圆柱型轴承具有更加优良的动力学性能，同时合理的减小椭圆型轴承的顶隙能够显著提高转子涡动稳定性。项目成果完善了船舶尾轴承的瞬态润滑与动力特性理论，为我国深度研制具有自主知识产权的高技术船舶以及深海钻井平台的推进和动力定位系统提供理论支撑。