Gear Dynamics Analysis With Turbulent Journal Bearings Mounted Hybrid Squeeze Film Damper—Chaos and Active Control Analysis

2014 ◽  
Vol 10 (1) ◽  
Author(s):  
Cai-Wan Chang-Jian
Keyword(s):  
Chaotic Motion ◽  
Journal Bearing ◽  
Complex Dynamics ◽  
Journal Bearings ◽  
Squeeze Film ◽  
Maximum Lyapunov Exponent ◽  
Control Analysis ◽  
Bifurcation Diagrams ◽  
Squeeze Film Damper ◽  
Chaotic Vibrations

The hybrid squeeze film damper mounted turbulent journal bearing–gear system is proposed in this paper. The nonlinear dynamics of a gear pair supported by such bearing is studied. Numerical results show that, due to the nonlinear factors of lubricant film force, the trajectory of the pinion demonstrates a complex dynamics with dimensionless unbalance parameters. Poincaré maps and bifurcation diagrams are used to analyze the behavior of the pinion trajectory in the horizontal direction. The maximum Lyapunov exponent is used to determine if the system is in a state of chaotic motion. In order to avoid the nonsynchronous chaotic vibrations, an increased proportional gain kp = 0.1 is applied to control this system. It is shown that the pinion trajectory will leave chaotic motion to periodic motion in the steady state under control action.

Subharmonic and Chaotic Motions of a Hybrid Squeeze-Film Damper-Mounted Rigid Rotor With Active Control

2002 ◽  
Vol 124 (2) ◽  
pp. 198-208 ◽  
Author(s):  
Chieh-Li Chen ◽  
Her-Terng Yau ◽  
Yunhua Li
Keyword(s):  
Lyapunov Exponent ◽  
Active Control ◽  
Chaotic Motion ◽  
Numerical Results ◽  
Operating Conditions ◽  
Squeeze Film ◽  
Speed Ratio ◽  
Maximum Lyapunov Exponent ◽  
Rigid Rotor ◽  
Squeeze Film Damper

The hybrid squeeze-film damper bearing with active control is proposed in this paper. The pressure distribution and the dynamics of a rigid rotor supported by such bearing are studied. A PD (proportional-plus-derivative) controller is used to stabilize the rotor-bearing system. Numerical results show that, due to the nonlinear factors of oil film force, the trajectory of the rotor demonstrates a complex dynamics with rotational speed ratio s. Poincare´ maps, bifurcation diagrams, and power spectra are used to analyze the behavior of the rotor trajectory in the horizontal and vertical directions under different operating conditions. The maximum Lyapunov exponent and fractal dimension concepts are used to determine if the system is in a state of chaotic motion. Numerical results show that the maximum Lyapunov exponent of this system is positive and the dimension of the rotor trajectory is fractal at the nondimensional speed ratio s=3.0, which indicate that the rotor trajectory is chaotic under such operation condition. In order to avoid the nonsynchronous chaotic vibrations, an increased proportional gain is applied to control this system. It is shown that the rotor trajectory will leave chaotic motion to periodic motion in the steady state under control action.

Rotordynamic Evaluation of a Large High-Speed Rotor Equipped With Flexure Pivot Journal Bearings and Integral Squeeze Film Damper

2021 ◽  
Author(s):  
Giuseppe Vannini ◽  
Alice Innocenti ◽  
Filippo Cangioli ◽  
Kim Jongsoo
Keyword(s):  
High Speed ◽  
Oil And Gas ◽  
Journal Bearing ◽  
Journal Bearings ◽  
System Level ◽  
Squeeze Film ◽  
Squeeze Film Damper ◽  
Process Gas ◽  
Gas Market ◽  
High Flexibility

Abstract The current oil and gas market trends lead the compressor OEMs to increase the rotational speed and maximize the efficiency given a target power output. Especially when applied to large process gas centrifugal compressors, characterized by high-flexibility ratio, the achievement of these targets pushes the rotordynamic design towards its limit in terms of API requirements. Tiling pad journal bearings (TPJBs) are commonly adopted in high-speed applications for their inherent stability characteristics that permit to ensure the rotordynamic stability and eliminate self-induced sub-synchronous vibrations. The experimental activities subject of this paper aim to assess, for the first time, the rotordynamic behaviour of a large dummy rotor (6 meter long and total weight of 8 tons) equipped with Flexure Pivot tilting-pad journal bearing and Integral squeeze film damper (ISFD). This system level testing program has been performed in the Authors’ high-speed balancing bunker properly equipped with special instrumentation such as: flow meters and pad temperature probes to monitor journal bearing behaviour, displacement probes to measure rotor vibrations relative to the bearings. The main objective of the experimental activity is the full assessment of the rotordynamic response and the selection of the best configuration to target the design requirements (e.g. FPJB and “Active ISFD” vs. FPJB and “Inactive ISFD”).

Stability Characteristics of a Journal Bearing Mounted in an Uncentralized Squeeze Film Damper

1991 ◽  
Vol 113 (3) ◽  
pp. 584-589
Author(s):  
Yuichi Sato ◽  
H. Fujino ◽  
H. Sakakida ◽  
S. Hisa
Keyword(s):  
Steam Turbine ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Squeeze Film ◽  
Squeeze Film Damper ◽  
The Stability ◽  
Bearing Analysis

This paper describes the stability of a journal bearing mounted in an uncentralized squeeze film damper. It is known that mounting a journal bearing in a centralized squeeze film damper improves the bearing stability. From a practical viewpoint, however, it is difficult to centralize journal bearings which support a heavy rotor, such as a steam turbine. Experimentally, we show that a journal bearing can be stabilized by mounting in an uncentralized squeeze film damper. The effect of clearance of a squeeze film damper is investigated. By using short bearing analysis, rotor trajectories are calculated. Calculated results also shows stability improvement.

Numerical investigation of dynamic and hydrodynamic characteristics of the pad in the fluid pivot journal bearing

2021 ◽  
pp. 135065012110330
Author(s):  
Tuyen Vu Nguyen ◽  
Weiguang Li
Keyword(s):  
Computational Models ◽  
Journal Bearing ◽  
Squeeze Film ◽  
Hydrodynamic Characteristics ◽  
Hydrodynamic Properties ◽  
Squeeze Film Damper ◽  
Lubricant Oil ◽  
Oil Flow ◽  
Flow Through ◽  
Bearing System

The dynamic and hydrodynamic properties of the pad in the fluid pivot journal bearing are investigated in this paper. Preload coefficients, recess area, and size gap, which were selected as input parameters to investigate, are important parameters of fluid pivot journal bearing. The pad’s pendulum angle, lubricant oil flow through the gap, and recess pressure which characterizes the squeeze film damper were investigated with different preload coefficients, recess area, and gap sizes. The computational models were established and numerical methods were used to determine the equilibrium position of the shaft-bearing system. Since then, the pendulum angle of the pad, liquid flow, and recess pressure were determined by different eccentricities.

scholarly journals On Error Torques of Squeeze-Film Cylindrical Journal Bearings

1968 ◽  
Vol 90 (1) ◽  
pp. 191-198
Author(s):  
C. H. T. Pan ◽  
T. Chiang
Keyword(s):  
Radial Displacement ◽  
High Performance ◽  
Journal Bearing ◽  
Rotational Symmetry ◽  
Mathematical Problem ◽  
Journal Bearings ◽  
Squeeze Film

The squeeze-film bearing has been considered for the output axis of high performance gyroscopes. Viewing this application, it is important that the parasitic torque of the bearing be very small. In the case of a squeeze-film journal bearing, parasitic torque can result from tolerance effects which disrupt rotational symmetry of the bearing. This problem has been studied by assuming ellipses for the tolerances of the journal and bearing surfaces as well as the squeeze motion, respectively. Each tolerance effect is assumed to be axially uniform. The mathematical problem is linearized with respect to each of the tolerances and the radial displacement of the journal. It was found that the parasitic torques do not depend on the radial displacement of the journal. The parasitic torques result from interactions among the three types of tolerance effects while each of the tolerances alone will not lead to any torque. Numerical estimates based on the geometry of a typical gyroscope and current fabrication practice shows such parasitic torques can seriously impair the accuracy of the gyroscope.

The Load Capacity of Short Journal Bearings With Oscillating Effective Speed

1964 ◽  
Vol 86 (2) ◽  
pp. 348-353 ◽  
Author(s):  
B. K. Gupta ◽  
R. M. Phelan
Keyword(s):  
Significant Contribution ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Numerical Solutions ◽  
Load Capacity ◽  
Journal Bearings ◽  
Squeeze Film ◽  
Major Conclusion ◽  
Angular Velocities ◽  
Effective Speed

The development of the Reynolds equation for the general case of dynamically loaded journal bearings is extended to include the concept of an effective speed that combines in one term the angular velocities of the journal, bearing, and load. Numerical solutions for the short-bearing approximation are presented for the case of an oscillating effective speed and a load that is constant or varying sinusoidally. Results are compared with available experimental data. The major conclusion is that for those cases involving an oscillating effective speed and a reversing load, the only significant contribution to load capacity comes from the squeeze film and the wedge film can safely be ignored when designing such bearings.

Nonlinear Analysis of Porous Squeeze Film Damper-Mounted a Rotor with Non-Linear Suspension and Roughness Effect

2011 ◽  
Vol 121-126 ◽  
pp. 1687-1691
Author(s):  
Cai Wan Changjian ◽  
Hsiang Chen Hsu ◽  
Jiann Lin Chen ◽  
Guan I Wu
Keyword(s):  
Squeeze Film ◽  
Maximum Lyapunov Exponent ◽  
Roughness Effect ◽  
Squeeze Film Damper ◽  
Highly Nonlinear ◽  
Transverse Roughness ◽  
Rotor Center ◽  
Numerical Research ◽  
Nonlinear Regimes ◽  
Bearing System

This work studies a numerical research undertaken to investigate the dynamic behaviors of porous squeeze film damper mounted a rotor considering longitudinal and transverse roughness effect under nonlinear suspension. The dynamic response of the rotor center and bearing center are studied. The analysis methods employed in this study are inclusive of the dynamic trajectories of the rotor center and bearing center, Poincaré maps and bifurcation diagrams. The maximum Lyapunov exponent analysis is also used to identify the onset of chaotic motion. The modeling results provide some useful insights into the design and development of rotor-bearing system for rotating machinery that operate in highly rotational speed and highly nonlinear regimes.

Determination of the Integration Constant for Squeeze Films in Infinitely Long Journal Bearings

1970 ◽  
Vol 92 (1) ◽  
pp. 179-180
Author(s):  
D. C. Kuzma
Keyword(s):  
Arbitrary Constant ◽  
Journal Bearing ◽  
Load Capacity ◽  
Journal Bearings ◽  
Integration Constant ◽  
Squeeze Film ◽  
Positive Pressure ◽  
Limiting Case

The complete film solution for the squeeze film in an infinitely long journal bearing contains an arbitrary constant. When only positive pressure regions are retained, this constant influences the load capacity. Several different values have been used for this constant. Its value is determined here so that the infinitely long journal bearing is the limiting case of the finite journal bearing.

scholarly journals A Dynamical Study of a Rotor Supported by a Radial Journal Bearing Incorporating a Spherical Squeeze Film Damper

2021 ◽  
Vol 31 (5) ◽  
pp. 10-16
Keyword(s):  
Journal Bearing ◽  
Equations Of Motion ◽  
Spherical Shape ◽  
Squeeze Film ◽  
Dynamical Study ◽  
Squeeze Film Damper ◽  
Mechanical Waves ◽  
Squeeze Film Dampers ◽  
The Stability ◽  
Nonlinear Equations Of Motion

The reduction of noises, vibration, and mechanical waves transmitting through water from the shells of submarines is essential to their safe operation and travelling. Vibrations from the rotors of the engines are widely deemed as one of the main sources to which engineers have tried to attenuate with various designs. Squeeze-film dampers can be easily integrated into rotor-bearing structures in order to lower the level of vibrations caused by rotors out of balance. For this advantage, squeeze-film dampers are widely used in air-turbine engines. This paper presents preliminary results of a numerical simulation of a shaft running on a journal bearing integrated with a squeeze-film damper and evaluates the capacity in reducing vibrations concerning the stability of static equilibrium of the shaft journal center. The proposed damper is designed in spherical shape with self-aligning capacity. The results were obtained using finite difference method and numerical integration of the full nonlinear equations of motion.

A novel memristor-based chaotic system with line equilibria and its complex dynamics

2021 ◽  
Author(s):  
Dengwei Yan ◽  
Musha Ji’e ◽  
Lidan Wang ◽  
Shukai Duan
Keyword(s):  
Lyapunov Exponent ◽  
Chaotic System ◽  
Dynamic Characteristics ◽  
Complex Dynamics ◽  
Circuit Simulation ◽  
Basins Of Attraction ◽  
Maximum Lyapunov Exponent ◽  
Bifurcation Diagrams ◽  
Structure Complexity ◽  
Complexity Algorithm

Memristor, as a nonlinear element, provides many advantages thanks to its superior properties to design different chaotic circuits. Thus, a novel four-dimensional double-scroll chaotic system with line equilibria as well as two unstable equilibria based on the flux-memristor model is proposed in this paper. The effects of initial values and parameters on the dynamic characteristics of the system are studied in detail by means of phase diagrams, Lyapunov exponent spectrums, bifurcation diagrams, two-parameter bifurcation diagrams and basins of attraction. Besides, a series of complex phenomena in the system, such as sustained chaos, bistability, transient chaos and coexisting attractors are observed, proving that the chaotic system has rich dynamic characteristics. Also, spectral entropy (SE) complexity algorithm and [Formula: see text] complexity algorithm based on structure complexity are adopted to analyze the complexity of the system. Additionally, PSPICE circuit simulation and Micro-Controller Unit (MCU) hardware experiment are carried out to verify the correctness of theoretical analysis and numerical simulation. Finally, the pulse chaos synchronization is achieved from the perspective of maximum Lyapunov exponent, and numerical simulations demonstrate the occurrence of the proposed system and practicability of the pulse synchronization control.

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