STUDY ON WHOLE MACHINE BALANCING METHOD FOR COAXIAL DUAL-ROTOR SYSTEM WITH LITTLE ROTATING SPEED DIFFERENCE

2004 ◽  
Vol 40 (08) ◽  
pp. 40 ◽  
Author(s):  
Zhixin Zhang
Keyword(s):  
Rotor System ◽  
Rotating Speed ◽  
Speed Difference

scholarly journals Vibration characteristics of triple-gear-rotor system in compressed air energy storage under variable torque load

2021 ◽  
Vol 104 (1) ◽  
pp. 003685042098705
Author(s):  
Xinran Wang ◽  
Yangli Zhu ◽  
Wen Li ◽  
Dongxu Hu ◽  
Xuehui Zhang ◽  
...  
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Element Model ◽  
Rotor System ◽  
Dynamic Responses ◽  
System Response ◽  
Rotating Speed ◽  
Torque Load ◽  
Set Up ◽  
Two Stages

This paper focuses on the effects of the off-design operation of CAES on the dynamic characteristics of the triple-gear-rotor system. A finite element model of the system is set up with unbalanced excitations, torque load excitations, and backlash which lead to variations of tooth contact status. An experiment is carried out to verify the accuracy of the mathematical model. The results show that when the system is subjected to large-scale torque load lifting at a high rotating speed, it has two stages of relatively strong periodicity when the torque load is light, and of chaotic when the torque load is heavy, with the transition between the two states being relatively quick and violent. The analysis of the three-dimensional acceleration spectrum and the meshing force shows that the variation in the meshing state and the fluctuation of the meshing force is the basic reasons for the variation in the system response with the torque load. In addition, the three rotors in the triple-gear-rotor system studied show a strong similarity in the meshing states and meshing force fluctuations, which result in the similarity in the dynamic responses of the three rotors.

Feasibility investigation of a compressor rotor supported by gas foil bearings with inhomogeneous bump foils

2021 ◽  
pp. 135065012110046
Author(s):  
Hao Li ◽  
Haipeng Geng ◽  
Bo Wang ◽  
Wei Zheng
Keyword(s):  
Critical Speed ◽  
Rotor System ◽  
Experimental Result ◽  
Test Results ◽  
Rotating Speed ◽  
Foil Bearings ◽  
Dynamic Coefficients ◽  
High Order Harmonic ◽  
Compressor Rotor ◽  
Operating Points

In this paper, a rotordynamic experiment on a compressor rotor system is presented and the feasibility of gas foil bearings with inhomogeneous bump foils is verified. A push–pull device is designed to obtain the stiffness curve and the nominal clearance of foil bearings. Operating points and dynamic coefficients of the rotor system at each rotating speed are predicted. In rotordynamic analysis, an alternative model of the impeller is proposed and the critical speed is predicted by employing the finite element method, in which the dynamic coefficients of inhomogeneous foil bearings are taken into account. Compared with the experimental result, the accuracy of the prediction for the critical speed is verified to be about 14% error. Two sets of foil bearings with 22 and 41 μm nominal clearance are manufactured and tested. Test results indicate that the vibration amplitude can be greatly reduced by diminishing the bearing clearance. When foil bearings with 22 μm clearance are used, the high-order harmonic frequencies of rotor vibration are significantly inhibited, and the amplitude of the rotating frequency is obviously restricted. Thus, the foil bearing with inhomogeneous bump foils tested in this paper can meet the speed requirement of the compressor when the nominal clearance is set at 22 μm.

scholarly journals Dynamic characteristics of the gear-rotor system in compressed air energy storage considering friction effects

2021 ◽  
Vol 12 (1) ◽  
pp. 677-688
Author(s):  
Xinran Wang ◽  
Wen Li ◽  
Dongxu Hu ◽  
Xingjian Dai ◽  
Haisheng Chen
Keyword(s):  
Energy Storage ◽  
Friction Coefficient ◽  
Dynamic Characteristics ◽  
Surface Friction ◽  
Rotor System ◽  
Compressed Air ◽  
Contact Temperature ◽  
Tooth Surface ◽  
Compressed Air Energy Storage ◽  
Rotating Speed

Abstract. The tooth surface friction effects and the resulting tooth surface contact temperature are important factors for the dynamic characteristics of a gear-rotor system in compressed air energy storage (CAES). Therefore, a 3∘ of freedom finite-element model of the system is set up in which the lubrication state of the gear pair, tooth surface friction, contact temperature of the tooth surface, backlash and unbalanced excitation are considered. The friction coefficient is calculated according to the variation of the lubrication state, and the tooth surface contact temperature is derived based on the friction coefficient. The tooth profile deformation caused by the change in the contact temperature is calculated, and the resulting effects on backlash and comprehensive meshing stiffness are considered. The influence of rotating speed, torque load and viscosity of lubricating oil on the system response is studied, and the variation of the friction coefficient, flash temperature of the tooth surface, pressure of the tooth surface and so on are discussed in detail. The results indicate that when the friction coefficient is derived according to the variation of the lubrication state, the variation of the contact temperature of the tooth surface with rotating speed is quite different from that calculated based on a friction coefficient which is set artificially. This leads to a new variation of the dynamic response of the gear-rotor system, and the method of stabilizing the operation of the system is put forward based on the optimization curve for the operation of the system. The results obtained in this paper will provide a reference for the study and design of a gear-rotor system in CAES.

Dynamic characteristics analysis of blade-casing rubbing faults with abradable coatings

2020 ◽  
pp. 095440622094155
Author(s):  
Junhong Zhang ◽  
Xin Lu ◽  
Jiewei Lin ◽  
Liang Ma ◽  
Huwei Dai
Keyword(s):  
Rotor System ◽  
Rotating Speed ◽  
Fundamental Frequencies ◽  
Abradable Coating ◽  
Characteristics Analysis ◽  
Blade Tip ◽  
System Vibration ◽  
Initial Clearance ◽  
Abradable Coatings ◽  
Dynamic Characteristics Analysis

In this paper, a dynamic model of a “0-2-1” rotor system with rubbing fault between blade and abradable coated casings is developed. The sub-model of rubbing force considers scraping work energy of coating, casing stiffness, and initial clearance between blade tip and casing. A rotor rig is established and samples of abradable coatings are introduced into the rubbing experiment. Vibration characteristics of the rotor system under blade-casing rubbing fault are analyzed. Effects of rotating speed and initial clearance on the rub force and the system vibration are studied. Results show that the vibration of rotor focuses on the fundamental and multiple fundamental frequencies due to the blade-casing rubbing with the abradable coating. The multiple fundamental frequencies, the 2 × and 3 × in particular, are greatly affected by the rotating speed. The fractional harmonic frequencies are strongly influenced by the initial clearance between the blade tip and casing. Besides, the rotating speed and the initial clearance between the blade tip and abradable coating on the casing also affect the amplitude and distribution of the rub force.

Simulation and Experiment Analyses on Resonance for a Rotor System With Elastic Supports

2007 ◽  
Author(s):  
Qingkai Han ◽  
Li Wang ◽  
Hongliang Yao ◽  
Bangchun Wen
Keyword(s):  
Rotor System ◽  
Dynamical Equations ◽  
Interesting Phenomenon ◽  
Nonlinear Dynamical ◽  
Elastic Supports ◽  
Rotating Speed ◽  
Frequency Capture ◽  
Resonance Vibrations ◽  
Simulation And Experiment ◽  
Pass Through

There exist different vibration patterns when a rotor system runs up and down through its critical speed, in one of them, is the interesting phenomenon called frequency capture. Based on a specially designed rotor system which is supported by elastic supports, the resonance vibrations of frequency capture and pass-through are discussed both in time and frequency domains. The nonlinear dynamical equations are described in details for the system. The vibrations of capture, when the rotating speed is locked, are compared with normal pass-through by numerical simulations and experiments. Also the instantaneous displacement trajectories, 3D FFT waterfalls and phase space portraits are calculated and demonstrated for the above two resonance vibrations. In addition, the periodical motions are discussed for capture motions using both amplitude spectra and pseudo-Poincare mappings of simulation and experiment data.

scholarly journals Nonlinear vibration behaviors of marine rotor system coupled with floating raft-airbag-displacement restrictor under ship heaving motion

2021 ◽  
Vol 13 (12) ◽  
pp. 168781402110673
Author(s):  
Xuan Xie ◽  
Ming Li ◽  
Junwei Wang
Keyword(s):  
Nonlinear Vibration ◽  
Rotor System ◽  
Rotating Speed ◽  
Floating Raft ◽  
Runge Kutta Method ◽  
Axis Orbit ◽  
Steady State Responses ◽  
Time Domain Response ◽  
Frequency Domain Response ◽  
State Responses

To study the nonlinear vibration behaviors of rotor system coupled with floating raft-airbag-displacement restrictor under ship heaving motion, the dynamic model is established considering the effect of heaving motion, its steady-state responses are numerically obtained using Runge-Kutta method and the results are surveyed by tools such as the spectrum waterfall diagram, time-domain response, frequency-domain response, axis orbit, and Poincaré map. The effects of rotating speed, ship heaving amplitude, and its frequency on the nonlinear dynamic behavior of the system are mainly studied. The results show that the responses of the rotor and raft are of obvious nonlinear behaviors such as amplitude jumping, bifurcation, and chaos due to the effects of nonlinear oil film force and ship heaving motion. With the increase of rotating speed, the motion of rotor and raft presents quasi-periodic and chaotic vibrations. Ship heaving amplitude and its frequency all have great effect on the vibration of rotor and raft; as heaving amplitude or frequency increases, the motion state of rotor and raft changes, and the amplitude of raft increases significantly. The displacement restrictor can effectively limit the vibrating displacements of the raft when ship heaving amplitude or its frequency is large.

scholarly journals Theoretical and Experimental Study on the Transient Time-Frequency Characteristics of the Bending-Torsional Coupling Motions of a Rub-Impact Dual-Rotor System

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Tian Gao ◽  
Shuqian Cao ◽  
Tiancheng Zhang
Keyword(s):  
Friction Coefficient ◽  
Fault Detection ◽  
High Speed ◽  
Rotor System ◽  
Bending Vibration ◽  
Transient Time ◽  
Rotating Speed ◽  
Time Frequency ◽  
Runge Kutta Method ◽  
Torsional Coupling

This paper focuses on the fault characteristics of the bending and torsional motions of a rub-impact dual-rotor system caused by aircraft flight maneuvers. The equations of the bending-torsional coupling motion of a dual-rotor system are established considering a low-pressure rotor rub-impact fault and the transient barrel roll flight of an aircraft. The 4th Runge-Kutta method with varied steps is used to obtain the bending and torsional responses. Then, the influences of the system parameters, including the rub-impact stiffness, friction coefficient, and rotating speed, on the bending and torsional motions of the dual-rotor system are investigated in detail. At last, a rotor rubbing experiment is carried out, verifying the validity of the simulation results. The results show that the rub-impact stiffness affects bending vibration significantly and the torsional motion is sensitive to the friction coefficient. Correspondingly, the torsional responses show apparent fractional fault frequencies and rotating fault frequencies within the whole region of the rub-impact stiffness. The bending responses can only display fault frequencies at certain rub-impact stiffness. As for the rotating speed, the torsional responses are also more effective than the bending responses for the rub-impact fault detection at the low- and high-speed regions. The results will contribute to a comprehensive basis for the rub-impact fault detection.

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