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 Bifurcation and dynamic behavior analysis of a rotating cantilever plate in subsonic airflow

2020 ◽  
Vol 41 (12) ◽  
pp. 1861-1880
Author(s):  
Li Ma ◽  
Minghui Yao ◽  
Wei Zhang ◽  
Dongxing Cao
Keyword(s):  
Aerodynamic Force ◽  
Shear Deformation Theory ◽  
Phase Portraits ◽  
Cantilever Plate ◽  
Dynamical Equations ◽  
Nonlinear Dynamical ◽  
Rotating Speed ◽  
Geometric Relationship ◽  
Asymptotic Perturbation ◽  
Nonlinear Geometric

AbstractTurbo-machineries, as key components, have a wide utilization in fields of civil, aerospace, and mechanical engineering. By calculating natural frequencies and dynamical deformations, we have explained the rationality of the series form for the aerodynamic force of the blade under the subsonic flow in our earlier studies. In this paper, the subsonic aerodynamic force obtained numerically is applied to the low pressure compressor blade with a low constant rotating speed. The blade is established as a pre-twist and presetting cantilever plate with a rectangular section under combined excitations, including the centrifugal force and the aerodynamic force. In view of the first-order shear deformation theory and von-Kármán nonlinear geometric relationship, the nonlinear partial differential dynamical equations for the warping cantilever blade are derived by Hamilton’s principle. The second-order ordinary differential equations are acquired by the Galerkin approach. With consideration of 1:3 internal resonance and 1/2 sub-harmonic resonance, the averaged equation is derived by the asymptotic perturbation methodology. Bifurcation diagrams, phase portraits, waveforms, and power spectrums are numerically obtained to analyze the effects of the first harmonic of the aerodynamic force on nonlinear dynamical responses of the structure.

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.

Dynamic Loading on Turbofan Blades Due to Bird-Strike

2011 ◽  
Vol 133 (12) ◽  
Author(s):  
Sunil K. Sinha ◽  
Kevin E. Turner ◽  
Nitesh Jain
Keyword(s):  
Dynamic Loading ◽  
Time History ◽  
Material Model ◽  
Bird Strike ◽  
Dynamical Equations ◽  
Nonlinear Dynamical ◽  
History Of ◽  
Measured Strain ◽  
Dynamic Loading Condition ◽  
Fan Blade

In the present paper, a hydrodynamic bird material model made up of water and air mixture is developed, which produces good correlation with the measured strain-gauge test data in a panel test. This parametric bird projectile model is used to generate the time-history of the transient dynamic loads on the turbofan engine blades for different size birds impacting at varying span locations of the fan blade. The problem is formulated in 3D vector dynamics equations using a nonlinear trajectory analysis approach. The analytical derivation captures the physics of the slicing process by considering the incoming bird in the shape of a cylindrical impactor as it comes into contact with the rotating fan blades modeled as a pretwisted plate with a camber. The contact-impact dynamic loading on the airfoil produced during the bird-strike is determined by solving the coupled nonlinear dynamical equations governing the movement of the bird-slice in time-domain using a sixth-order Runge-Kutta technique. The analytically predicted family of load time-history curves enables the blade designer to readily identify the critical impact location for peak dynamic loading condition during the bird-ingestion tests mandated for certification by the regulatory agencies.

Non-Linear Dynamic Stability of Shallow Reticulated Spherical Shells

2011 ◽  
Vol 142 ◽  
pp. 107-110
Author(s):  
Ming Jun Han ◽  
You Tang Li ◽  
Ping Qiu ◽  
Xin Zhi Wang
Keyword(s):  
Three Dimensional ◽  
Dynamical Equations ◽  
Third Order ◽  
Spherical Shells ◽  
Nonlinear Dynamical ◽  
Linear Dynamic ◽  
The Third ◽  
Displacement Mode ◽  
Nonlinear Forced Vibration ◽  
The Stability

The nonlinear dynamical equations are established by using the method of quasi-shells for three-dimensional shallow spherical shells with circular bottom. Displacement mode that meets the boundary conditions of fixed edges is given by using the method of the separate variable, A nonlinear forced vibration equation containing the second and the third order is derived by using the method of Galerkin. The stability of the equilibrium point is studied by using the Floquet exponent.

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.

Motion of AMB Rotor in Backup Bearings

2002 ◽  
Vol 124 (3) ◽  
pp. 460-464 ◽  
Author(s):  
Sheng Zeng
Keyword(s):  
Chaotic Motion ◽  
Nonlinear Response ◽  
Linear Models ◽  
Rotating Speed ◽  
Harmonic Motion ◽  
Power Failure ◽  
Resonance Frequencies ◽  
Speed Range ◽  
Pass Through ◽  
Bearing System

This paper studies numerically the motion of an AMB rotor when it is supported only by backup bearings. Unlike a linear rotor-bearing system, which always undergoes a harmonic motion, the nonlinear AMB rotor-backup bearing system will undergo irregular or chaotic motion at some rotating speeds. The simulations show that in a wide rotating speed range there are several extra resonance frequencies, which are different from those appearing in well-known linear models. When a power failure occurs to AMB machinery, the AMB rotor should pass through all these resonance frequencies. Under some conditions, the full clearance whirl motion of the rotor in backup bearings will happen, which may lead to damage. In this paper several measures that could reduce the nonlinear response and hence avoid the full clearance motion are discussed.

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