Desenvolvimento do modelo numérico de uma bancada de rotor flexível suportada por um mancal sem contato baseado em filme de ar espremido

Abstract

Acoustic levitation is a method in which an object is levitated at a stable position against gravity by acoustic radiation force produced by intense sound waves. This technique can be divided into standing wave acoustic levitation and near-field acoustic levitation. In the first type of levitation, small objects are suspended near the pressure nodes of a standing wave created between a transducer and a reflector. On the other hand, in the near-field acoustic levitation a planar object is placed close to a vibrating surface, so a thin layer of air, known as squeeze film, is trapped in the clearance between the two surfaces. Even though the near-field acoustic levitation is a recently developed technique, it has been widely investigated in the last few decades for the development of a new type of non-contact bearing, known as squeeze film bearing. In this context, the present work aims to develop a numerical model based on the Finite Element Method to predict the dynamic behavior of a flexible rotor supported by two bearings, one of them being the squeeze film air bearing presented by Feng et al. (2018). For the case where the squeeze film air bearing is represented by a non-linear model, the dynamic behavior of the rotor is determined from the simultaneous resolution of motion and Reynolds equations. Now for the case where the squeeze film air bearing is represented by a linear model, the bearing forces are determined from the stiffness and damping coefficients associated. The numerical results presented in this work demonstrate that the non-contact bearing proposed by Feng et al. (2018) is adequate to be used in rotating machines that support low loads and operate outside critical speeds.