Dynamic response in non-perpendicular stiff main directional rotors using coordinate transformation

In rotordynamic systems, the majority of problems are due to an imbalance or misalignment, and it is possible to simulate their effects via mathematical models. The generation of a dynamic response in numeric rotor monitoring commonly uses special matrix models with several degrees of freedom, corresponding to the simulated equipment. However, in the first models for systems larger than 2 dof, their use is not very practical, while for modal analysis, generation of a response is not possible in positions distinct from the horizontal and vertical coordinate axes. This article presents a proposed solution for developing numeric turbogenerator models using modal analysis, which permits the generation of a dynamic response observed by an imaginary sensor in any angular position around the bearing. This allows a priori evaluation of the balancing weights and their angular positioning, reducing the risks of damage to the equipment, installation, and personnel, due to errors committed during the determination of modal weight balance. A graphical comparison is made between the spatial matrix model and uncoupled single degree of freedom systems, in order to later present the application in a numerical modal model of a field turbomachinery with 14 modes of vibration. © 2015, The Brazilian Society of Mechanical Sciences and Engineering.

Coordinate transformation; Field turbogenerator; Imbalance; Modal model; Numerical models; Response diagrams; Rotatory systems Degrees of freedom (mechanics); Dynamic response; Modal analysis; Turbines; Turbogenerators; Angular positioning; Co-ordinate transformation; Graphical comparison; Imbalance; Modal models; Response diagrams; Single degree of freedom systems; Vertical coordinates; Numerical models

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