• Title/Summary/Keyword: Rotor Dynamic Analysis

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Dynamic Characteristic Analyses of a Bearingless Helicopter Rotor Systems (무베어링 헬리콥터 로터 시스템의 동특성 해석)

  • Kee, Young-Jung;Yun, Chul-Yong;Kim, Seung-Ho
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2011.10a
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    • pp.52-56
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    • 2011
  • Recently, KARI(Korea Aerospace Research Institute) has been developing a modern 11.5m diameter four bladed bearingless main rotor system, and this rotor system can be used for 7,000lb class helicopter. Flexbeam and torque tube can be considered as the key structural components, and large elastic twist of flexbeam induced by pitch control motion of torque tube can influence the nonlinear aeroelastic behavior. In this paper, the dynamic characteristic analysis results of bearingless rotor system were presented. In order to construct a input model and validate the analysis procedures, calculated results using the comprehensive helicopter analysis program CAMRAD II were compared with the measured natural frequencies and lag damping data from small-scale wind tunnel test. Next, the analysis model was extended to a full-scale model, and the dynamic analysis results were presented.

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Dynamic Characteristic Analyses of a Bearingless Helicopter Rotor System (무베어링 헬리콥터 로터 시스템의 동특성 해석)

  • Kee, Young-Jung;Yun, Chul-Yong;Kim, Doeg-Kwan;Kim, Seung-Ho
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.22 no.2
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    • pp.187-192
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    • 2012
  • Recently, KARI(Korea Aerospace Research Institute) has been developing a modern 11.5 m diameter four bladed bearingless main rotor system, and this rotor system can be used for 7,000 lb class helicopter. Flexbeam and torque tube can be considered as key structural components, and large elastic twist of flexbeam induced by pitch control motion of torque tube can influence the nonlinear aeroelastic behavior. In this paper, the dynamic characteristic analysis results of bearingless rotor system were presented. In order to construct a input model and validate the analysis procedures, calculated results using the comprehensive helicopter analysis program CAMRAD II were compared with the measured natural frequencies and lag damping data from small-scale wind tunnel test. Next, the analysis model was extended to a full-scale model, and the dynamic analysis results were presented.

Dynamic Analysis of Effect of Number of Balls on Rotor-Bearing System

  • Hwang, Pyung;Nguyen, Van Trang
    • Tribology and Lubricants
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    • v.29 no.4
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    • pp.248-254
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    • 2013
  • This paper presents a numerical model for investigating the structural dynamic response of an unbalanced rotor system supported on deep groove ball bearings. The aim of this work is to develop a numerical model for investigating the effect of the number of balls on the dynamic characteristics of the rotor ball bearing system. The fourth-order Runge-Kutta numerical integration technique has been applied. The results are presented in the form of time displacement responses and frequency spectra. The analysis demonstrates that the model can be used as a tool for predicting the nonlinear dynamic behavior of the rotor ball bearing system under different operating conditions. Moreover, the study may contribute to a further understanding of the nonlinear dynamics of rotor bearing systems.

Dynamic Characteristics of Indeterminate Rotor Systems with Angular Contact Ball Bearings Subject to Axial and Radial Loads

  • Hong, Seong-Wook;Kang, Joong-Ok;Yung C. Shin
    • International Journal of Precision Engineering and Manufacturing
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    • v.3 no.2
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    • pp.61-71
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    • 2002
  • This paper presents the dynamic analysis of indeterminate rotor systems with angular contact ball bearings subject to axial and radial loads. The reaction forces against applied radial loads significantly influence the dynamic characteristics of angular contact ball bearings. However, the reaction forces are hard to determine in the case of indeterminate rotor-bearing systems. To this end, this paper proposes a finite element model for indeterminate rotor systems with angular contact ball bearings. An improved bearing model is adopted which is originated from the Harris's bearing dynamic model. The bearing model is also extended to include centrifugal forces due to the ball and inner ring. This paper utilizes a new iterative algorithm for general, indeterminate rotor systems with angular contact ball bearings. This examples are provided to illustrate the dynamic characteristics of rotor systems with angular contact ball bearings subject to axial and radial loads. The experimental and numerical results prove that the proposed method is useful for the dynamic analysis of indeterminate rotor systems with angular contact ball bearings.

A Comparison of Dynamics of Rotor Systems for Different Internal Damping Models (분포 내부 감쇠 모형에 따른 회전체 계 동특성 비교 연구)

  • 박종혁;전봉석;강중옥;홍성욱
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.11b
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    • pp.838-843
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    • 2001
  • Internal damping plays an important role in some rotor dynamic systems with the use of various materials for shafts, for example, composite material. However, although the effects of internal damping have been investigated for a couple of decades, there are several different internal damping models in use, none of which are accepted as the most reliable model. The purpose of this paper is to compare the results of dynamic analysis of rotor systems with several different internal damping models. The exact dynamic element method is used to formulate and analyze the problem. The simulation results provided in this paper may be useful for the dynamic analysis of high rotor systems subject to significant internal damping.

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Dynamic Behavior Analysis of Rotor-Bearing System for Rotary Compressor (로터리 압축기 회전체-베어링계의 동적 거동해석)

  • 김태학
    • Journal of Advanced Marine Engineering and Technology
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    • v.23 no.2
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    • pp.244-251
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    • 1999
  • Large dynamic loads act on the rotor in rotary compressors. There are unbalance forces due to eccentric rotation parts and gas forces induced by the pressure difference between compression and suction gases. Rotor-journal bearing system is nonlinear since the stiffness and damping coef-ficients of the lubrication oil film are not constant in the bearings. in this paper the program for predicting the behaviors of rotor-journal bearing system of rotary compressor is developed. Finite element modeling is used to analyze the flexible rotor. The numerical results are compared with experimental results.

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Dynamic Analysis of an Automatic Dynamic Balancer in a Rotor with the Bending Flexibility (축의 굽힘효과를 고려한 회전체에 장착된 자동평형장치의 동적해석)

  • Bang, In-Chang;Chung, Jin-Tai
    • Proceedings of the KSME Conference
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    • 2000.11a
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    • pp.629-634
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    • 2000
  • Dynamic behavior of an automatic dynamic balancer is analyzed by a theoretical approach. Using Lagrange's equation, we derive the non-linear equations of motion for an automatic dynamic balancer equipped in a rotor with the bending flexibility with respect to the rectangular coordinate. Considering the rotor bending flexibility we analyze out-of-plane vibrations as well as in-plane vibrations of the automatic dynamic balaner. The time responses are computed from the non-linear equations by using a time integration method. We also investigate the effect of rotor flexibility on the behavior of the automatic dynamic balancer

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Dynamic Analysis of Rotating Bodies Using Model Order Reduction (모델차수축소기법을 이용한 회전체의 동해석)

  • Han, Jeong-Sam
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2011.04a
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    • pp.443-444
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    • 2011
  • This paper discusses a model order reduction for large order rotor dynamics systems results from the finite element discretization. Typical rotor systems consist of a rotor, built-on parts, and a support system, and require prudent consideration in their dynamic analysis models because they include unsymmetric stiffness, localized nonproportional damping and frequency dependent gyroscopic effects. When the finite element model has a very large number of degrees of freedom because of complex geometry, repeated dynamic analyses to investigate the critical speeds, stability, and unbalanced response are computationally very expensive to finish within a practical design cycle. In this paper, the Krylov-based model order reduction via moment matching significantly speeds up the dynamic analyses necessary to check eigenvalues and critical speeds of a Nelson-Vaugh rotor system. With this approach the dynamic simulation is efficiently repeated via a reduced system by changing a running rotational speed because it can be preserved as a parameter in the process of model reduction. The Campbell diagram by the reduced system shows very good agreement with that of the original system. A 3-D finite element model of the Nelson-Vaugh rotor system is taken as a numerical example to demonstrate the advantages of this model reduction for rotor dynamic simulation.

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A Study on the dynamic characteristics of rotor systems supported by angular contact ball bearings with the axial displacement preload varied (각접촉 볼 베어링의 정위치 예압 변화에 따른 회전체 계 동특성 변화 연구)

  • 강중옥;홍성욱
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1997.10a
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    • pp.389-392
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    • 1997
  • This paper presents the dynamic analysis and experiment for rotor systems supported by angular contact ball bearings subjected to axial displacement preload. A dynamic software, which has been developed by the authors for the analysis of rotor systems supported by angular contact ball bearings, is used to simulate a uniform shaft system supported by two angular contact ball bearings with the axial displacement preload varied. Experiments are also performed to validate the simulation. An experimental system is constructed which consists of a uniform shaft, two bearings and a device for adjusting the axial displacement preload. Through a series of simulation and experiment, the dynamic characteristics of rotor systems with angular contact ball bearings subject to axial displacement preload are investigated.

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Dynamic Analysis of an Automatic Dynamic Balancer in a Rotor with the Bending Flexibility (축의 굽힘효과를 고려한 회전체에 장착된 자동평형장치의 동적해석)

  • Jeong, Jin-Tae;Bang, In-Chang
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.7
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    • pp.1125-1130
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    • 2001
  • Dynamic behaviors of an automatic dynamic balancer are analyzed by a theoretical approach. Using the polar coordinates, the non-linear equations of motion for an automatic dynamic balancer equipped in a rotor with the bending flexibility are derived from Lagrange equation. Based on the non-linear equation, the stability analysis is performed by using the perturbation method. The stability results are verified by computing dynamic response. The time responses are computed from the non-linear equations by using a time integration method. We also investigate the effect of the bending flexibility on the dynamics of the automatic dynamic balancer.