叶轮机叶片流致振动的数值预测与错频抑颤机制

During the research and development, as well as in-service of aircraft gas turbine engine, the flow-induced vibration (mainly including flutter and forced response) frequently leads to high cycle fatigue and decreases the structural reliability of fan and compressor rotor blades and the other thin-shelled components. This project focuses on the research and development of the numerical prediction methodology of flow-induced vibration of rotor blades in the axial flow compressor with the emphasis on flutter and forced response, in which the research will be done on the following respects: the development of energy method based on phase-shifted periodic boundary for flutter prediction, the investigation on the mechanism of mistuning of blades and its effects on suppressing flutter with the consideration of real structural coupling, the investigation on the sensitivity of intentional mistuning to the random mistuning on the effects for flutter suppesion, the effects of radial tip clearance of baldes on the aeroelastic stability of axial compressor rotor, and the development of a fully coupled nonliear approach for the aeroelasticity problem of rotor blades in a compressor by the comparison of the numerial prediction results with the data measured on the test rig to assessing and validating the developed model, algorithm and the software. The implementation and achievements of this project will be helpful to enhancing the understanding of aeroelastic phenomenon and mechanism, to grasping the effects of main influencing factors on flow-induced vibration, to decreasing the failure rate of components due to aeroelastic problems, and to providing the theory and method physically to solving and breaking through the high cycle fatigue problems of thin-walled structures (such as blades) due to the vibration in gas turbine engines.

航空燃气涡轮发动机在研制和使用中常因流致振动(主要包括颤振和强迫振动)引起风扇/压气机转子叶片等薄壁结构件的高循环疲劳失效问题，导致其结构可靠性降低。本项目拟在颤振和强迫振动响应两个方面，针对轴流压气机转子叶片，开展气动弹性问题数值预测方法研究。主要研究内容包括：基于移相边界条件的能量法；考虑实际结构耦合因素下的错频抑颤机理及主控因素影响规律；错频抑颤效果对随机失调因素的敏感性；叶尖间隙对轴流压气机转子叶片气动弹性稳定性的影响规律；发展一种非线性深度耦合的气动弹性问题分析方法，并将数值预测结果与试验实测结果进行对比，以考核、验证所发展的模型、算法与软件工具。本项目研究有助于人们对轴流叶轮机械流致振动机制的认识，掌握主控参数的影响规律；并可为航空轴流压气机/风扇叶片设计提供有效的数值预测方法，减少由于气动弹性问题导致的结构失效，为从根本上突破与解决叶片等薄壁结构的高循环疲劳问题提供理论方法。

航空航天动力与推进系统，以及一般工业用旋转机械中的叶片常出现振动导致的结构疲劳失效，其中航空燃气涡轮发动机中风扇和压气机转子叶片尤为突出，其深层次原因是叶片结构与绕流场的相互作用。本项目主要研究航空叶轮机械气动弹性问题数值预测方法，重点针对叶片颤振和强迫响应这两种气动弹性现象发展了高精度、高效、多层次的数值预测方法，包括能量法、特征值法及时域法；对工程中可用以抑制叶片颤振的手段，即错频转子的抑颤规律及其机理进行了研究，并着重分析了转子叶尖径向间隙大小这一主控因素对转子叶片气动弹性稳定性的影响规律。主要研究成果包括：基于移相边界条件发展了可考虑叶间相位角的高效能量法；发展了能够准确考虑结构耦合刚度影响的气动弹性特征值法，并明确了有意错频和随机失调对转子叶片气动弹性稳定性的影响规律；给出了叶尖间隙变化对转子叶片气动弹性稳定性的非单调影响规律；发展了可考虑耦合非线性的气动弹性数值预测方法。本项目有助于提高研究人员对轴流叶轮机械流固耦合振动机制的认识，掌握主控参数的影响规律；并可为航空轴流压气机/风扇叶片设计提供有效的数值预测方法，减少由于气动弹性问题导致的结构失效，为从根本上突破和解决航空燃气涡轮发动机在研制和使用中因流致振动(主要包括颤振和强迫响应)引起的风扇/压气机转子叶片等薄壁结构件高循环疲劳问题提供理论方法，以及经与试验实测结果进行对比、考核验证的模型、算法和数值预测分析程序。