scholarly journals Estimation of the Dynamic Parameters of the Bearings in a Flexible Rotor System Utilizing Electromagnetic Excitation by a Built-In Motor

Actuators ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 1
Author(s):  
Yinsi Chen ◽  
Ren Yang ◽  
Naohiro Sugita ◽  
Jianpeng Zhong ◽  
Junhong Mao ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Rotor System ◽  
Radial Excitation ◽  
Maximum Relative Error ◽  
Fe Model ◽  
Dynamic Parameters ◽  
Flexible Rotor ◽  
Electromagnetic Excitation ◽  
Excitation Force ◽  
Good Agreement

Estimation of the dynamic parameters of bearings is essential in order to be able to interpret the performance of rotating machinery. In this paper, we propose a method to estimate the dynamic parameters of the bearings in a flexible rotor system. By utilizing the electromagnetic excitation generated by a built-in PM motor and finite element (FE) modeling of the rotor, safe, low-cost, and real-time monitoring of the bearing dynamics can be achieved. The radial excitation force is generated by injecting an alternating d-axis current into the motor windings. The FE model of the rotor and the measured frequency responses at the motor and bearing locations are used to estimate the dynamic parameters of the bearings. To evaluate the feasibility of the proposed method, numerical simulation and experiments were carried out on a flexible rotor system combined with a bearingless motor (BELM) having both motor windings and suspension windings. The numerical simulation results show that the proposed algorithm can accurately estimate the dynamic parameters of the bearings. In the experiment, the estimates made when utilizing the excitation force generated by the motor windings are compared with the estimates made when utilizing the excitation force generated by the suspension windings. The results show that most of the stiffness and damping coefficients for the two experiments are in good agreement, within a maximum error of 8.92%. The errors for some coefficients are large because the base values of these coefficients are small in our test rig, so these coefficients are sensitive to deviations. The natural frequencies calculated from the dynamic parameters estimated from the two experiments are also in good agreement, within a maximum relative error of 3.04%. The proposed method is effective and feasible for turbomachines directly connected to motors, which is highly significant for field tests.

Theoretical Analysis and Numerical Simulation on the Hydraulic Expansion of Double-Layered Tubes

2008 ◽  
Author(s):  
Fujun Liu ◽  
Jinyang Zheng ◽  
Shoubao Ding ◽  
Xiaolian Guo
Keyword(s):  
Numerical Simulation ◽  
Stress Distribution ◽  
Theoretical Analysis ◽  
Suitable Condition ◽  
Stress And Strain ◽  
Maximum Relative Error ◽  
Hoop Strain ◽  
Whole Process ◽  
Good Agreement

The quality of hydro-expanded double-layered tubes depends on the hydro-expanding pressure. Therefore, it is very important to determine the range of the hydro-expanding pressure accurately during the fabrication of double-layer tubes. According to theories of elasticity and plasticity, the responses of double-layered tubes subjected to five kinds of cases were analyzed during the hydro-expanding process. And the stress and strain for inner and outer tubes of double-layered tubes were discussed. By using the relation of deformed compatibility of hoop strain, suitable condition of hydraulic expansion and variable range of hydro-expanding pressure were obtained, and the calculating formulas between the hydro-expanding pressure and residual contact pressure was derived. Use the non-linear FEA MSC.patran/marc code to simulate the deformation and stress distribution, the whole process of hydraulic expansion was numerically investigated, in which the nonlinearities of the material, geometry and contact were all taken into account. The results show that the range of the hydro-expanding pressure from the numerical simulation is in good agreement with those from theoretical calculation with a maximum relative error of 6.52%. The investigation on the hydraulic expansion of double-layered tubes may guide the engineering design and provide references for further research.

Estimation of Active Magnetic Bearings (AMB) Dynamic Parameters and Residual Mass Imbalance Using FEM With PID Controller and Identification Algorithm of a Flexible Rotor System Fully Levitated on AMB

2019 ◽  
Author(s):  
Bala Murugan S. ◽  
R. K. Behera
Keyword(s):  
Pid Controller ◽  
Rotor System ◽  
Magnetic Bearings ◽  
Identification Algorithm ◽  
Dynamic Parameters ◽  
Active Magnetic Bearings ◽  
Flexible Rotor ◽  
Residual Mass ◽  
Mass Imbalance ◽  
Least Squares Fit

Abstract The dynamic analyses of rotating systems are always a testing task to obtain the definite results. This paper carries the dynamic modelling, analysis and identification of coupled flexible rotor system supported by an auxiliary Active Magnetic Bearings (AMBs). An identification algorithm is used to estimate the dynamic parameters of AMB, and rotor residual mass imbalance. The proposed algorithm is a right method for the analysis of fully levitated rotor on AMBs. Finite element method is used to model the dynamic flexible rotor system with PID controller. A conventional dynamic condensation technique is implemented in the development of identification algorithm to overcome the difficulty in numerical simulation. The least-squares fit technique is deployed to estimate the dynamic parameters in frequency domain. Then the algorithm is extended to find the misalignment forces and moments at the coupling point. Numerical study is carried to check the correctness of the algorithm. The proposed algorithm is yet to be tested to experimental results from a fully levitated rotor test rig supported with AMBs.

Dynamics and stability analysis of a flexible liquid-filled rotor in a constant thermal environment

2021 ◽  
pp. 107754632110224
Author(s):  
Guangding Wang ◽  
Wenjun Yang ◽  
Huiqun Yuan
Keyword(s):  
Thermal Environment ◽  
Rotor System ◽  
Flexible Rotor ◽  
Rotatory Inertia ◽  
Rayleigh Beam ◽  
Comparison Results ◽  
The Stability ◽  
Spinning Speed ◽  
Thermoelastic Theory ◽  
Good Agreement

In this study, the dynamics and stability of a flexible rotor containing liquid in a constant thermal environment are investigated. According to thermoelastic theory, the thermal axial force exerted on the rotor is calculated by using the analytical method. A spinning Rayleigh beam is used as a simplified model of the rotor. Applying the Hamilton principle, the governing equation of motion for the flexible liquid-filled rotor system is derived. Using the obtained model, the stability prediction model and the critical spinning speed for the rotor system are formulated. To demonstrate the validity of the developed model, the present analysis is compared with the results reported in the previous study, and good agreement is observed from the comparison results. Finally, numerical results based on the obtained model are performed for a better understanding of the parameters including filling parameters, mode number, rotatory inertia and thermal effect on the stability, and critical spinning speed of the rotor system.

Research on Dynamic Model of Rotors with Bearing Misalignment

2014 ◽  
Vol 539 ◽  
pp. 3-8 ◽  
Author(s):  
De Xin Ren ◽  
Jie Hong ◽  
Cun Wang
Keyword(s):  
Dynamic Model ◽  
Rotor System ◽  
Flexible Rotor ◽  
Bending Rigidity ◽  
Lagrange Method ◽  
Motion Equations ◽  
Excitation Force ◽  
Aero Engines ◽  
The Relationship ◽  
Mechanics Characteristics

Based on the structural and mechanics analysis of aero-engines rotor system, the dynamic model of the flexible rotor system with multi-supports are presented in order to solve the bearing misalignment problem of rotor system in aero-engines. The motion equations are derived through Lagrange method. The relationship between structural and mechanics characteristics parameters are built up. Finally, the dynamic influence of bearing misalignment on rotor system is divided into three kinds: additional rotor bending rigidity, additional bearing misalignment excitation force and additional imbalance. The equations suggest that additional imbalance excitation force activates the nonlinearity on rotor system and an additional 2× excitation force might appear.

Modelling of Misaligned Rotor Systems in Aero-Engines

2012 ◽  
Author(s):  
Jun Li ◽  
Jie Hong ◽  
Yanhong Ma ◽  
Dayi Zhang
Keyword(s):  
Dynamic Model ◽  
Rotor System ◽  
Flexible Rotor ◽  
Lagrange Equations ◽  
Rotor Systems ◽  
Nonlinear Properties ◽  
Aero Engine ◽  
Series Of Experiments ◽  
Aero Engines ◽  
Good Agreement

Based on the analysis of structural and dynamic characteristics, a dynamic model of flexible rotor system under misalignment and unbalance excitation in aero-engine was developed through Lagrange equations. The model describes the mechanism and influencing factors of nonlinear properties of misaligned rotors. Then some numerical simulations were performed in order to get the vibration response in time and frequency domain. The results suggest that the rotor system and its coupling may behave in a complex and nonlinear way with the excitation of misalignment and unbalance. The response of the system contains 1× and 2× harmonics, and the spectrum signature closely relate to the misalignment magnitude and the distribution of unbalance mass. A series of experiments were also designed to verify the dynamic model. Their characteristics of response are in good agreement.

scholarly journals An analytical investigation for optimizing the support stiffness and positions of the bearings of a flexible rotor system

2020 ◽  
Author(s):  
Jing Liu ◽  
Changke Tang
Keyword(s):  
Optimization Design ◽  
Rotor System ◽  
Mode Shapes ◽  
Rotational Inertia ◽  
Fe Model ◽  
Flexible Rotor ◽  
Fe Method ◽  
Critical Speeds ◽  
Rotor Systems ◽  
Flexible Rotor Systems

Abstract The support stiffness and positions of the bearings can greatly affect the vibrations of flexible rotor systems. However, most previous works only focused on the effect of the support stiffness of the bearings on the critical speeds of the rigid rotor systems or modal characteristics including natural frequencies and mode shapes, which missed the combine effects of the support stiffness and positions of the bearings. To overcome this issue, an analytical dynamic model of a flexible rotor system based on the finite element (FE) method is proposed. The model considers the support stiffness of the bearings and rotational inertia of the rotor system. The frequency equation of the rotor system is established for solving the critical speeds. The critical speeds and modal deformations of the system from the presented model and the numerical model based on a commercial software are compared to verify the effectiveness of the proposed FE model. The effects of the support stiffness and positions of the bearings on the critical speeds of the flexible rotor system are analyzed. The results show that the critical speeds are positively correlated with the support stiffness. The critical speeds of the flexible rotor system are also greatly affected by the support positions of the bearing. This study can provide some guidance for the optimization design method of the support stiffness and positions of the bearings in the flexible rotor systems.

Modeling of mass transfer in biofilms in oscillatory flow conditions using k-ɛ turbulence model

2003 ◽  
Vol 3 (1-2) ◽  
pp. 201-207
Author(s):  
H. Nagaoka ◽  
T. Nakano ◽  
D. Akimoto
Keyword(s):  
Numerical Simulation ◽  
Mass Transfer ◽  
Turbulence Model ◽  
Uptake Rate ◽  
Oscillatory Flow ◽  
Substrate Uptake ◽  
Flow Conditions ◽  
Mass Transfer Mechanism ◽  
Substrate Uptake Rate ◽  
Good Agreement

The objective of this research is to investigate mass transfer mechanism in biofilms under oscillatory flow conditions. Numerical simulation of turbulence near a biofilm was conducted using the low Reynold’s number k-ɛ turbulence model. Substrate transfer in biofilms under oscillatory flow conditions was assumed to be carried out by turbulent diffusion caused by fluid movement and substrate concentration profile in biofilm was calculated. An experiment was carried out to measure velocity profile near a biofilm under oscillatory flow conditions and the influence of the turbulence on substrate uptake rate by the biofilm was also measured. Measured turbulence was in good agreement with the calculated one and the influence of the turbulence on the substrate uptake rate was well explained by the simulation.

Field Observation and Simulation of Sediment Resuspension in a Shallow Lake

1988 ◽  
Vol 20 (6-7) ◽  
pp. 263-270 ◽  
Author(s):  
K. Otsubo ◽  
K. Muraoka
Keyword(s):  
Numerical Simulation ◽  
Shallow Lake ◽  
Water Wave ◽  
Field Data ◽  
Sediment Resuspension ◽  
Field Research ◽  
Lake Kasumigaura ◽  
Bed Erosion ◽  
Current Water ◽  
Good Agreement

The dispersion and resuspension of sediments in Takahamairi Bay basin of Lake Kasumigaura were studied by means of field research and numerical simulation. The field data on wind direction and velocity, lake current, water wave, and turbidity were shown. Based on these results, we discuss how precipitated sediments were resuspended in this shallow lake. To predict the turbidity and the depth of bed erosion, a simulation model was established for this lake. The calculated turbidity showed good agreement with the field data. According to the simulated results, the turbidity reaches 200 ppm, and the bed is eroded several millimeters deep when the wind velocity exceeds 12 m/s in the lake.

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