scholarly journals Resonant phenomena in nonlinear vertical rotor systems

2021 ◽  
Vol 112 (4) ◽  
Author(s):  
T.M. Ospan ◽  
A.E. Ibraev
Keyword(s):  
Rotor Systems ◽  
Vertical Rotor ◽  
Resonant Phenomena

Experimental Verification of a Combi-Bearing Model for Vertical Rotor Systems

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Jean-Claude Luneno ◽  
Jan-Olov Aidanpää ◽  
Rolf Gustavsson
Keyword(s):  
Dynamic Models ◽  
Contact Point ◽  
Element Model ◽  
Experimental Results ◽  
Small Scale ◽  
Rotor Systems ◽  
Vertical Rotor ◽  
Bearing Design ◽  
Rotor Bearings ◽  
Rotor Dynamic

Combi-bearing is a combined thrust-journal bearing design used in vertical hydropower rotors. The dynamic characteristics of this component (combi-bearing) were analytically modeled by Luneno et al. (2011, “Model Based Analysis of Coupled Vibrations Due to the Combi-Bearing in Vertical Hydroturbogenerator Rotors,” ASME J. Vib. Acoust., 133, p. 061012). This analytic model was inserted into a finite element model of a vertical rotor rig and numerically simulated. In this paper, the simulated vertical rotor-bearings system is a small-scale vertical machine constructed to validate the analytically derived combi-bearing model. Good agreement was found between the simulation and experimental results. The simulation and experimental results showed that the journal (radial) bearing's position relative to the contact point between the combi-bearing's collar and the rotor influences the rotor system's fundamental natural frequencies. Therefore, the combi-bearing model needs to be included into rotor dynamic models. Neglecting the effect of this component may cause significant errors in the predicted results.

Misalignment in Combi-Bearing: A Cause of Parametric Instability in Vertical Rotor Systems

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Jean-Claude Luneno ◽  
Jan-Olov Aidanpää ◽  
Rolf Gustavsson
Keyword(s):  
Journal Bearing ◽  
Contact Point ◽  
Parametric Instability ◽  
Rotor Speed ◽  
Angular Misalignment ◽  
Rotor Systems ◽  
Asymmetric Structures ◽  
Rotating Systems ◽  
Vertical Rotor ◽  
Stationary Frame

The dynamic characteristics of the combi-bearing (combined thrust-journal bearing) in vertical rotor systems were analytically modeled and experimentally verified in the authors’ previous publications. An angular misalignment, which may be caused by a possible manufacturing or assembling error, is introduced in the combi-bearing’s rotating collar. A new model of the defective combi-bearing has been derived. The derived model shows that the angular misalignment in the combi-bearing’s rotating collar generates an asymmetry in the rotor system at the combi-bearing’s location. The rotor system’s stiffness in its two translational X and Y directions differ at the combi-bearing’s location. Constant parameters and/or coefficients in rotating asymmetric structures appear to change with time when observed in the stationary frame. These time dependent parameters (coefficients) are the source of the so-called parametric instability in rotating systems. If the collar angular misalignment is located in the X-Z plane all rotor motions in this plane at the contact point between the combi-bearing and the rotor will be coupled. A parametric instability is observed within certain ranges of the rotor speed, depending on the magnitude of the angular misalignment.

Reduction of structural vibrations with the piezoelectric stacks ring

2020 ◽  
Vol 64 (1-4) ◽  
pp. 729-736
Author(s):  
Jincheng He ◽  
Xing Tan ◽  
Wang Tao ◽  
Xinhai Wu ◽  
Huan He ◽  
...  
Keyword(s):  
Vibration Control ◽  
Mechanical Energy ◽  
Electrical Energy ◽  
Structural Vibrations ◽  
Rotor Systems ◽  
Fea Model ◽  
Piezoelectric Stacks ◽  
Shunt Damping ◽  
Reduction Effect ◽  
Euler Bernoulli Beam

It is known that piezoelectric material shunted with external circuits can convert mechanical energy to electrical energy, which is so called piezoelectric shunt damping technology. In this paper, a piezoelectric stacks ring (PSR) is designed for vibration control of beams and rotor systems. A relative simple electromechanical model of an Euler Bernoulli beam supported by two piezoelectric stacks shunted with resonant RL circuits is established. The equation of motion of such simplified system has been derived using Hamilton’s principle. A more realistic FEA model is developed. The numerical analysis is carried out using COMSOL® and the simulation results show a significant reduction of vibration amplitude at the specific natural frequencies. Using finite element method, the influence of circuit parameters on lateral vibration control is discussed. A preliminary experiment of a prototype PSR verifies the PSR’s vibration reduction effect.

Effects of Cyclic Pitch on Time Delayed Dynamics in Coaxial Rotor Systems

2021 ◽  
Author(s):  
Ethan S. Genter ◽  
Cory A. Seidel ◽  
David A. Peters
Keyword(s):  
Rotor Systems ◽  
Coaxial Rotor

ACCURACY RATING MEASUREMENT OF VIBRATION ELECTROMECHANICAL DEVICES

2019 ◽  
Vol 1 (7) ◽  
pp. 42-45
Author(s):  
V. A. Golubkov ◽  
V. F. Shishlakov ◽  
A. G. Fedorenko ◽  
E. Yu. Vataeva
Keyword(s):  
Technical Condition ◽  
Rotor System ◽  
Vibration Measurement ◽  
Random Errors ◽  
Mass Ratio ◽  
Signal Flow Graph ◽  
Bond Graphs ◽  
Rotor Systems ◽  
Electromechanical Devices ◽  
Main Components

Electromechanical devices consist mainly of rotor systems. Vibration is the result of the interaction of the elements of the rotor system and is largely determined by the accuracy of manufacturing elements at the production stage and defects arising in the process of operation. The main components of the rotor systems that affect vibration are bearings. To determine the technical condition of the bearings and the service life of the rotor system, it is necessary to accurately measure the unobservable vibrations of the rotor. The article describes the model of the channel for measuring the vibration of an electromechanical system, built using the apparatus of bond graphs. The transfer function is obtained by analyzing the signal flow graph. The systematic and random errors of vibration measurement are analyzed depending on the mass ratio between the system case and the vibration transducer for various sensor masses and attachment rigidity.

scholarly journals Erratum: Search for new non-resonant phenomena in high-mass dilepton final states with the ATLAS detector

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
G. Aad ◽  
◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
...  
Keyword(s):  
Atlas Detector ◽  
High Mass ◽  
Final States ◽  
Dilepton Final States ◽  
Resonant Phenomena

The Lagrangian in eq. (2.1) of JHEP11 (2020) 005 has an erroneous factor of 1/2. The analysis code used for the results reported in the paper does not have this factor. The results remain unchanged.

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