scholarly journals Coupled lateral-torsional vibration of a rotor system trained by gears. 6th Report. The relation between vibrations and gear noise.

1987 ◽  
Vol 53 (486) ◽  
pp. 370-378
Author(s):  
Takuzo IWATSUBO ◽  
Takao OHI ◽  
Ryoji KAWAI
Keyword(s):  
Torsional Vibration ◽  
Rotor System ◽  
Gear Noise

Nonlinear Dynamic Analysis on Planetary Gears-Rotor System in Geared Turbofan Engines

2019 ◽  
Vol 29 (06) ◽  
pp. 1950076 ◽  
Author(s):  
Lanlan Hou ◽  
Shuqian Cao
Keyword(s):  
Nonlinear Dynamic Analysis ◽  
Period Doubling ◽  
Nonlinear Behavior ◽  
Rotor System ◽  
Chaotic Motions ◽  
Planetary Gears ◽  
Gear Noise ◽  
Turbofan Engines ◽  
Vibration Responses ◽  
Nonlinear Analytical Model

Rotor fatigue and gear noise triggered by nonlinear vibration are the key concerns in Geared Turbofan (GTF) engine which features a new configuration by introducing planetary gears into low-pressure compressor. A nonlinear analytical model of the GTF planetary gears-rotor system is developed, where the torsional effect of rotor and pivotal parameters from gears are incorporated. The nonlinear behavior of the model can be obtained by focusing on the relative torsional vibration responses between gear and rotor. The torsional nonlinear responses are illustrated with bifurcation diagrams, the largest Lyapunov exponents (LLE), Poincaré maps, phase diagrams and spectrum waterfall. Numerical results reveal that the gears-rotor system exhibits abundant torsional nonlinear behaviors, including multiperiodic, quasi-periodic, and chaotic motions. Furthermore, the roads to chaos via quasi-periodicity, period-doubling scenario, mutation and intermittence are demonstrated. The ring gear stiffness at a low value can propel the system into chaos. The damping may complicate the motion, i.e. the system may enter chaos with increasing damping. These results provide an understanding of undesirable torsional dynamic motion for the GTF engine rotor system and therefore serve as a useful reference for engineers in designing and controlling such system.

Sensitivity Analysis and Application of Natural Frequency of Torsional Vibration of Rotor System

2008 ◽  
Author(s):  
Qing He ◽  
Dongmei Du
Keyword(s):  
Sensitivity Analysis ◽  
Electric Power ◽  
Natural Frequency ◽  
Torsional Vibration ◽  
Natural Frequencies ◽  
Electric Power System ◽  
Rotor System ◽  
Analysis Method ◽  
Turbine Generator ◽  
Sensitivity Analysis Method

The disturbance of electric power system makes large-scale turbine-generator shafts generate torsional vibration. A available method to restrain the torsional vibration of turbine-generator shafts is that all the natural frequencies of torsional vibration of turbine-generator shafts must keep away from the working frequency and its harmonic frequencies as well as all the frequencies that possibly bring on interaction between turbine-generator and electric power system so that the torsional resonation of shafts may not occur. A dynamic design method for natural frequencies of torsional vibration of rotor system based on sensitivity analysis is presented. The sensitivities of natural frequency of torsional vibration to structure parameters of rotor system are obtained by means of the theory of sensitivity. After calculated the torsional vibration dynamic characteristics of original shafts of a torsional vibration stand that simulates the real shafts of 300MW turbine-generator, the dynamic modification for the torsional vibration natural frequency is carried out by the sensitivity analysis method, which makes the first-five natural frequencies of torsional vibration of the stand is very close to the design object. It is proved that the sensitivity analysis method can be used to the dynamic adjustment and optimal design of real shafts of turbine-generator.

scholarly journals Study on the lateral and torsional vibration of single rotor-system using an integrated multi-body dynamics and finite element analysis

2020 ◽  
Vol 12 (10) ◽  
pp. 168781402096833
Author(s):  
Abdelrahman I A Eisa ◽  
Li Shusen ◽  
Wasim M K Helal
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Torsional Vibration ◽  
Rapid Development ◽  
Rotor System ◽  
Motor Speed ◽  
Element Analysis ◽  
Body Dynamics ◽  
Bearing Force ◽  
Multi Body

Due to rapid development in the industry, operating speeds and eccentricity produced undesirable vibrations which may lead to damage in bearings, seals, and lubrication systems. In the proposed paper, a novel analytical method was presented using an integrated multi-body dynamics and finite element analysis to simulate the lateral and torsional vibration. This method was applied to a proposed model of single rotor-system. In order to study the lateral and torsional vibration of the system profoundly, three markers were placed on the locations of the left and right bearings and the mass center of the shaft. The effects of bearing force caused by lateral and torsional vibrations were also analyzed. The results showed that the lateral vibration has a great effect on the dynamic of single rotor-system when lowering motor speed. It was found that, as motor speed increased, the motion of the system becomes more stable with steady fluctuates of the displacement response. The calculated natural frequency of SRS is compared with theoretical results to verify the transient solver. This novel method is practical in analyzing the lateral and torsional vibration of the SRS under various speeds and eccentricities.

Reducing Torsional Vibration in an Engine Cold-Test Cell for Improved Structural Reliability and Engine Assembly Defect Diagnostics

2009 ◽  
Author(s):  
Kamran A. Gul ◽  
Douglas E. Adams
Keyword(s):  
Torsional Vibration ◽  
Structural Reliability ◽  
Cold Test ◽  
Test Cell ◽  
Production Test ◽  
Torsional Vibrations ◽  
Gear Noise ◽  
Defect Diagnostics ◽  
Waveform Distortion

The driveline components of engine cold-test cells undergo large torsional vibrations during transient tests as the system resonances are excited by various engine harmonics. The excessive torsional vibrations not only compromise the structural reliability of the system but also make the fault detection process difficult by preventing accurate measurement of gear noise and by compromising the quality of diagnostic torque waveforms. This paper presents modeling of an engine cold-test cell and a methodology to quantify signal distortion levels by using the proposed distortion metrics which are based on harmonic order amplitude ratios. A rigorous validation of the simulation model using both torque amplitude and waveform distortion comparisons of experimental and simulation data is conducted. The model is used to identify the driveline inertia and stiffness parameters that can help reduce high torsional resonant amplitudes as well as waveform distortion. The design modifications are implemented in a production test cell which helped to control the torsional vibration and diagnostic signal degradation issues with a corresponding increase in the sensitivity to faults.

Analysis of Flexural and Torsional Vibration for Turbogenerator Shafts on Power Impact

2010 ◽  
Vol 139-141 ◽  
pp. 2498-2501
Author(s):  
Ling Xiang ◽  
Shi Xi Yang
Keyword(s):  
Torsional Vibration ◽  
Simulation Experiment ◽  
Flexural Vibration ◽  
Vibration Characteristics ◽  
Rotor System ◽  
Rigid Support ◽  
Turbine Generator ◽  
Torsion Vibration ◽  
Jeffcott Rotor ◽  
Faults Diagnosis

Based on a Jeffcott rotor system with rigid support, the math models of flexural and torsional vibration were built, and their vibration characteristics were concluded. A simulation experiment in this paper was designed about the flexural and torsional vibration of shafts on a simulated turbine generator during network impacts. By analysis, flexural and torsional vibration characteristics were obtained, and the results showed the shafts flexural vibration and torsional vibration were interacted with each other. It was provided that torsional vibration could inhibit the complex shafts exercise. A new idea was suggested that the characteristics of torsion vibration should be considered as the symptom of faults diagnosis

Rotor Instability Due to Coupled Effect of Lateral and Torsional Modes and Improper Bearing Design

1997 ◽  
Author(s):  
Yatao Zhang ◽  
Jari Nyqvist
Keyword(s):  
Theoretical Model ◽  
Torsional Vibration ◽  
Vibration Analysis ◽  
Rotor System ◽  
Squeeze Film ◽  
Vibration Problem ◽  
Coupled Effect ◽  
Bearing Design ◽  
The Stability ◽  
Bending Modes

Abstract This paper deals with a special subsynchronous vibration problem, namely rotor instability caused by partly coupled effect of torsional and bending modes and partly improper bearing design. A theoretical model is presented to investigate such complicated vibration problem. The analysis shows that a single bending or torsional vibration analysis is not enough to predict the stability of a geared rotor system, which includes a turbine, a gear, a generator, several bearings, a squeeze film damper and stators. Either a bearing design, which gives stability in single lateral vibration analysis, cannot guarantee the stability if a torsional vibration mode is involved. This indicates that the bearing design plays much more significant role in a geared rotor system. The theoretical model has been successfully applied to a steam turbine set, which experienced such kind of subsynchronous vibration, by modifying the original bearing design.

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