旋转输流管拉弯扭耦合振动研究

The cooling blade is the core component of the heavy-duty gas turbine, which is used under severe Service eonditions 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 ränge, 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. Furthermore,the contributions of structural dynamics modeling and the associated numerical methodologies presented herein are deemed suitable for inclusion as supplementary reading material in both undergraduate and graduate Vibration mechanics courses.