基于分形理论的干摩擦模型及燃气轮机叶片阻尼减振效应研究

Gas turbine is an important symbol of the national scientific and technological level, military strength and comprehensive national strength. Blade is the key component of gas turbine for energy conversion. It is the worst working conditions, most complex and most of the failed component. In order to protect the blades from vibration fatigue failure, designers usually use dry friction structure to increase the damping of blade system and hence reduce the amplitude of blade vibration level. Dry friction damping has the advantages of simplicity in structure and independence of temperature. In this project, based on fractal theory, a three-dimensional friction model is proposed with considering the contact interfaces features. Combining anti-aliasing time/frequency-domain method, and multi-modal method, the solution and analysis software is developed for the gas turbine blade system of the startup/shutdown process. The effects of frictional contact interface parameters on the dynamic behavior of dry friction damper blade are investigated. The dry friction damping experiment system of gas turbine blade is built. The dry friction damping effects of some heavy-duty gas turbine blades are studied by the experiment system. The mechanism of gas turbine blade vibration startup/shutdown process is revealed combining the theoretical and experimental results. Finally, it is to propose the friction interface design guide-lines and formed the interface design method. The investigation of project will provide a theoretical basis for the friction damping design of gas turbine blade.

燃气轮机是国家科技水平、军事实力、综合国力的重要标志之一。叶片是燃气轮机实现能量转换的关键部件，也是工作环境最恶劣、结构最复杂、故障最多的部件。为减少叶片振动疲劳破坏，设计人员常采用干摩擦结构来增加叶片阻尼，减小叶片振动水平。干摩擦阻尼结构具有不受温度限制、减振效果好、简单易实施等优点。本项目基于分形理论，提出能够考虑接触面形貌参数的三维干摩擦模型，并综合抗混叠时频域交互方法和多模态降阶方法，开发燃气轮机启停机过程干摩擦阻尼叶片振动响应高效的计算分析软件，研究摩擦接触界面参数对干摩擦阻尼叶片宏观动力学行为的影响规律。建立燃气轮机叶片干摩擦减振实验系统，实验研究某重型燃气轮机叶片干摩擦阻尼减振效果。采用理论与实验相结合的方法揭示燃气轮机叶片在启停机过程中的减振机理，提出摩擦界面设计准则，形成界面的设计方法。为燃气轮机叶片摩擦阻尼减振设计提供理论依据。

叶片是燃气轮机实现能量转换的关键部件，也是工作环境最恶劣、结构最复杂、故障最多的部件。为减少叶片振动疲劳破坏，设计人员常采用干摩擦结构来增加叶片阻尼，减小叶片振动水平。干摩擦阻尼结构具有不受温度限制、减振效果好、简单易实施等优点。本项目建立了基于分形理论的三维干摩擦接触微动滑移模型，能够考虑接触面形貌参数、正压力对接触刚度的影响，并能够描述摩擦运动过程中接触面粘滞、滑移、分离状态。综合抗混叠时频域交互方法和多模态降阶方法，开发了燃气轮机启停机过程干摩擦阻尼叶片振动响应的计算分析软件，研究了接触面初始正压力、接触面粗糙度、摩擦系数、接触面积等接触界面参数对干摩擦阻尼叶片宏观动力学行为的影响规律。建立燃气轮机叶片干摩擦减振实验系统，实验中通过施加叶根底部的径向作用力来模拟叶根离心力，以形成燕尾型叶片与轮缘接触面的承载力；在叶身中间施加周向谐波激振力模拟周期性的气流力。测量不同模拟离心力、燕尾角度、表面粗糙度、接触面积等参数下燕尾型叶根叶片试验件的振动响应以及不同模拟离心力下燃气轮机压气机叶片的振动响应，研究各参数变化对叶片的干摩擦阻尼减振效果。采用理论与实验相结合的方法揭示燃气轮机叶片在启停机过程中的减振机理，提出了摩擦界面设计准则，初步形成界面的设计方法。为燃气轮机叶片摩擦阻尼减振设计提供理论依据。