【摘要】 冷却叶片是重型燃气轮机的核心构件，服役于严峻工况，常常因振动过量而失效。准确掌握冷却叶片振动机理，对重型燃气轮机叶片进行合理化设计与维护具有实际意义。以NACA0012翼型叶片为例，基于Euler-Bernoulli梁理论将模型简化为含不等大双通道单轴对称性的旋转悬臂输流管，利用假设模态法与Lagrange法建立了轴向-弦向-挥舞-扭转四自由度耦合动力学模型。通过和文献结果对比，确认了该研究建立动力学模型的准确性。研究了流体流速、输流管转速、拉伸-弦向耦合和挥舞-扭转耦合效应等对系统固有频率的影响。研究发现：转速对各自由度刚化效应影响不同，导致复杂的模态顺序交换；拉伸-弦向耦合和挥舞-扭转耦合会引发模态转向现象，导致不同阶振动频率降低或升高；对于长细比较大的Euler-Bernoulli梁来说，单轴对称截面的非对称性影响主要集中在挥舞-扭转耦合；在一定转速范围内，挥舞-扭转耦合效应可能诱发系统发生颤振失稳。更多还原

【Abstract】 The cooling blade is the core component of the heavy-duty gas turbine, which is used under severe service conditions and often fails due to excessive vibration. It is of practical significance to accurately understand the vibration mechanism of cooling blades for design and maintenance of gas turbine blades. In this paper, a NACA0012 airfoil blade was taken as an example. The blade was simplified into a rotating cantilever flow tube with a single-axisymmetric section, which contained unequal large double channels, based on the Euler-Bernoulli beam theory. An axial-chord-flap-torsion coupling dynamic model was established by using the assumed mode method and the Lagrange method. By comparing the results with the reference, the accuracy of the dynamic model in this study was confirmed. The effects of fluid flow velocity, infusion tube rotation speed, axial-chord coupling and flap-torsion coupling effect on the natural frequencies of the system were studied. It is found that the rotational speed has different effects on the stiffening effect of each degree of freedom, resulting in complex modal sequence exchange phenomenon. The axial-chord couplings, and the flap-torsion couplings could induce the modal steering phenomenon, resulting in a decrease or increase in the different natural frequencies. For Euler-Bernoulli beams with large slenderness, the influence of the single-axisymmetric section mainly focuses on the flap-torsional stiffness coupling. Within a certain speed range, the flap-torsion coupling effects may induce flutter instability in the system. In addition, the axial force showing a hardening effect on the torsional vibration of one-dimensional components, as discussed in present paper, represents an extension and advancement of the material concerning one-dimensional wave equations within the current curriculum of vibration mechanics.更多还原