by National Aeronautics and Space Administration, For sale by the National Technical Information Service in [Washington, DC, Springfield, Va .
Written in English
|Statement||prepared by: J. Walton ... [et al.].|
|Series||NASA contractor report -- 183942., NASA contractor report -- NASA CR-183942.|
|Contributions||Walton, J., United States. National Aeronautics and Space Administration.|
|The Physical Object|
Internal friction effect on high speed rotor stability using motion equation, noting bearing support flexibility and damping role Discover the world's research 17+ million membersAuthor: Edgar Gunter. On Rotor Internal Damping Instability A thesis submitted to the University of London for the degree of Doctor of Philosophy by Mohamed A Kandil Department of Mechanical Engineering Imperial College London December Restricted access: This thesis contains intellectual property of the author. The first role of internal friction consists of decreasing the level of effective damping during rotor subsynchronous and backward precessional vibrations caused by some other instability mechanisms. The second role of internal frication consists of creating rotor instability, i.e., causing self-excited subsynchronous : A. Muszynska and D. E. Bently. Vol. 49 () Stability of rotor systems There are three main sources to these kind of instabilities. First the internal friction or damping of a ﬂexible rotor shaft can lead to unstable lateral vibrations. This is surprising, because normally friction applied to a system will damp the free vibrations.
Overhung Rotors. Pumps. Rotordynamics. Squeeze Film Dampers. Stability. Time Transient. Torsional Vibrations. Turbines and Generators. Turbochargers. Whirl Motion. Paper “The Influence of Internal Friction on the Stability of High Speed Rotors,”. Abstract. This chapter presents the fundamental friction dynamics of drill strings and sucker rods. Concepts, modeling, and analysis on the topic of friction dynamics are presented, including advances in knowledge of the tool-rock interaction, couple axial and torsional dynamics, stick-slip whirl, and fully coupled dynamics of drill strings. Horizontal rotor systems on lubricated journal bearings may incur instability risks depending on the load and the angular speed. The instability is associated with the asymmetry of the stiffness matrix of the bearings around the equilibrium position, in like manner as the internal hysteretic instability somehow, where some beneficial effect is indeed obtainable by an anisotropic configuration Cited by: 1. instability and condition monitoring. Rotating Shaft Single-mass rotor The simplest case in rotor dynamics is the de Lavel rotor. The de Lavel rotor consists of a long, light shaft carrying a mid-span disk. Fig Single Mass rotor The mid-span disk has a centre File Size: KB.
In this paper two aspects of rotor internal friction are discussed: the first, a damping-reducing effect and the second, a cause of instability and self-excited vi- brations. The experimental test results document both aspects. 2. ROTOR MODEL WITH INTERNAL FRICTION To simplify the considerations, a symmetric rotor will be discussed. Internal friction has been known to be a cause of whirl instability in built-up rotors since the. early ’s. This internal damping tends to make the rotor whirl at shaft speeds greater than a. critical speed, the whirl speed usually being equal to the critical speed. Inhomogeneity Instability of Vertical Flows (Njn) Kelvin-Helmholtz Instability (Njo) Stratified Flow Instability (Njp) Annular Flow Instability (Njq) Two-Component Flow Videos Three-Component Flow Videos; Energy conversion (Nk) Introduction (Nka) Disperse Horizontal Flow Friction (Nkb) Homogeneous Flow Friction (Nkc) Heterogeneous Flow Friction. The destabilizing influence from friction in internal rotor joints is discussed. Several mechanisms of friction are analyzed: viscous damping, solid damping, dry friction, and micro-slip friction. They are compared on the basis of their energy input to the rotor whirl motion, assuming the whirl mode to known and unaffected by the by: 1.