Abstract：A vibration analysis method based on absolute node coordinate method is proposed and verified for the bearing cavity pipeline structure of an aircraft engine. First, based on the extended Lagrange equation, a theoretical model, considering the fluid-structure interaction comprehensively, is established. And the nonlinear equations of motion are discretized by the absolute node-coordinate method aiming to translate the formula into a solvable form. The static deformation of pipeline is then solved by equation decoupling. The specific process is deriving static equation including generalized force vector and stiffness matrix by omitting the time related terms, and the response of pipeline is obtained by solving the static equation by numerical iteration of node coordinates. The convergence analysis of the theoretical algorithm is then carried out to determine the optimal number of elements. Finally, compare the theoretical results with the fluid-structure interaction simulation results from two aspects: the accuracy of static deformation results and the effectiveness of natural frequency results. On the one hand, it is qualitatively shown that the static deformation of the theoretical results is consistent with the simulation results, and the displacement of a node on the pipeline is quantitatively analyzed. On the other hand, the nonlinear equation of motion is reduced to a linear equation, and the stability of the pipeline is analyzed to obtain the natural frequency of fluid-structure interaction simulation results and the theoretical results. The comparison results show that the theoretical results are more reliable. Further, the mechanism of static deformation is obtained from the flow field distribution at the bend of the pipeline. And the difference between the theoretical and simulated natural frequency results is explained from the perspective of flow field. The results of this study provide theoretical and technical support for the optimization design and vibration control of aero-engine bearing cavity pipeline.
2023, Vol. 44 
