Liquid Self-Balancing Device Effects on Flexible Rotor Stability

Abstract

Nearly a century ago, the liquid self-balancing device was first introduced by M. LeBlanc for passive balancing of turbine rotors. Although of common use in many types or rotating machines nowadays, little information is available on the unbalance response and stability characteristics of this device. Experimental fluid flow visualization evidences that radial and traverse circulatory waves arise due to the interaction of the fluid backward rotation and the baffle boards within the self-balancer annular cavity. The otherwise destabilizing force induced by trapped fluids in hollow rotors, becomes a stabilizing mechanism when the cavity is equipped with adequate baffle boards. Further experiments using Particle Image Velocimetry (PIV) enable to assess the active fluid mass fraction to be one-third of the total fluid mass. An analytical model is introduced to study the effects of the active fluid mass fraction on a flexible rotor supported by flexible supports excited by bwo different destabilizing mechanisms; rotor internal friction damping and aerodynamic cross-coupling. It is found that the fluid radial and traverse forces contribute to the balancing action and to improve the rotor stability, respectively.

Parametric Analysis of Nonlinear Oscillations of the “Rotor-Weakly Conductive Viscous Fluid-Foundation” System under the Action of a Magnetic Field

“…( 15) with boundary conditions Eqs. ( 7)-( 12) are consistent equations of motion of the rotor, foundation and weakly conductive viscous fluid [16]. To calculate the hydrodynamic force, the movement of the rotor and the foundation, it is convenient to represent them on the complex plane in the following form:…”

“…the system makes oscillations consisting of the sum of two harmonic oscillations [25]. In this case, the system performs a processional motion that differs from a circular precession [26].…”

Robust Estimation of the Unbalance of Rotor Systems Based on Sparsity Control of the Residual Model

“…Applications that can be commonly seen are steam turbines, compressors, wind turbines, and aeroengines. Balancing theory has been thoroughly studied, and several useful balancing methods have been developed in the last decades [1][2][3][4][5][6].…”

Nonlinear Vibrations of a Rotor-Fluid-Foundation System Supported by Rolling Bearings

“…At supercritical speeds fluid converts rotor rotation energy into its transverse vibration energy resulting in instability [7] and [8]. Analysis of experimental data shows that fluid in rotor cavities is often the main cause of unstable regimes [9] and [10]. The underlying physics is that the fluid centrifugal acceleration is opposite to the pressure gradient leading to violation of equilibrium [11] and [12].…”