Global Dynamics of Shaft Lines Rotating in Surrounding Fluids Application to Thin Fluid Films

Abstract

While often sufficiently accurate, approaches using rotor dynamics and bladed disc dynamics are not adapted to the study of certain important cases, i.e., when observing wheel/shaft coupling or when fluid elements are strongly coupled with local structural deformations. The approach proposed here is a step toward a global model of shaft lines. The whole flexible wheel/shaft assembly and the influence of specific fluid film elements are considered in a full threedimensional model. A modal projection associated with a grid located at the interface of the fluid and structural domains provides an efficient and adaptable coupling. The equations governing the whole system are solved within a time marching procedure which alternatively considers the equations of fluid and structure. The technique chosen is applied to two different test cases. The first is composed of a disc and a thin-walled shaft mounted on a hydrodynamic bearing. The second is intended for studying a more realistic structure composed of a shaft and a wheel coupled with a fluid film between the wheel and a casing. These applications make it possible to identify trends related to fluid effects and couplings between the flexible structural parts.High performances, reliability, and safety require a highly accurate prediction of turbomachine behavior. In this context, the work proposed aims at developing a global model of wheel/shaft assemblies rotating in surrounding fluids.Two uncoupled approaches are generally used to predict the dynamic behavior of rotating parts of machines.

Dynamic Finite Element Analysis of a Cylindrical Roller Bearing

“…With the rapid development of the computer technology, many problems on numerical contact analysis of bearing have been solved by using finite element analysis software ANSYS in which mix of different factors would be considered so that the analysis will be more close to practical engineering. It have been confirmed that the application of 3D finite element methods for computer analysis of the rotor system is very effective from the view of both higher modeling accuracy and information completeness points [1][2][3]. Liao [4] got the finite element stress analysis and strength evaluation of epoxy-steel cylinders subjected to impact push-off loads by using ANSYS/LS-DYNA module and experiments were carried out to measure the results.…”