Abstract
Extraction of features of a specific signal in fluid–structure interaction is among the hottest problems in the field of mechanics. Yet, a comprehensive study of such problems remains a challenge due to their high nonlinearity and multidisciplinary nature. The study presented in this article is focused on a particular engineering application of fluid–structure interaction. The governing equation of a spinning rotor submerged in an incompressible viscous fluid is modelled by means of well-established dissipative energy principle, yielding a highly coupled 3-degree-of-freedom system with strong nonlinear terms. A two-dimensional model of the Navier–Stokes equations for the incompressible flow is developed for the viscous fluid motion around the spinning rotor under high fluctuations induced by unbalance, rotor–stator rub and a crack. The extracted features through frequency spectrum, orbit patterns and rotor-coupled deflection revealed that the performances of rotor systems are highly impacted by the hydrodynamic terms which are the sources of multiple frequency response. The results showed that the complex fluid–rotor model yields good analysis of fault diagnosis, and responses at more than one parametric resonance appear and reach a point of complex feature extractions when more than one fault coexists in the system. Furthermore, a nonlinear denoising by thresholding the wavelet coefficients is performed to overcome the complexity of discretization and for effective multiple fault diagnoses.
Highlights
Rotating shafts are used in many sectors of industry, in particular, in the energy sector which is vital for any economic development
The risk of multiple faults is a significant form of rotor damage which can lead to disastrous failures if not detected in time
The fluctuation of stiffness values due to the presence of a crack and rub occurrences can affect the dynamic response of the system and increases the magnitude of the rotor vibrations to Department of Mechanical Engineering, Vaal University of Technology, Vanderbijlpark, South Africa
Summary
Rotating shafts are used in many sectors of industry, in particular, in the energy sector which is vital for any economic development. The techniques used for their studies were theoretical with an experimental validation Their conclusion was valid only in the case where a whirling radius of a rotor is sufficiently small compared to the gap width.[5] Some other experimental studies can be noted.[3,6,7,8] Behera et al.[6] demonstrated that the existence of cracks in a shaft submerged in a viscous medium can affect the amplitudes of vibration. The viscous fluid may cause self-excited vibrations and instabilities; the diagnosis of faults (unbalance, crack and rub coexist) in such medium are different from those observed in rotor models of elastic and rigid bodies only. The 3-DOF forms of coupled nonlinear equations of motion is written as describe the primary equation of computational fluid
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
