• 제목/요약/키워드: Whirl Natural

검색결과 23건 처리시간 0.019초

선회 고유진동수와 안정성을 고려한 회전자-베어링 시스템의 중량 최적설계 (Optimal Weight Design of Rotor-Bearing Systems Considering Whirl Natural Frequency and Stability)

  • 이동수;손윤호;최동훈
    • 대한기계학회논문집
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    • 제19권3호
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    • pp.639-646
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    • 1995
  • The objective of this study is to minimize the weight of a damped anisotropic roto-bearing system considering whirl natural frequency and stability. The system is modeled as an assemblage of rigid disks, flexible shafts and discrete bearings. The system design variables are the crosssectional areas of shaft elements and the properties of bearings. To analyze the system, the polynomial method which is derived by rearranging the calculations performed by a transfer matrix method is adopted. For the optimization, the optimization software IDOL (Integrated Design Optimization Library) which is based on the Augmented Lagrange Multiplier (ALM) method is employed. Also, an analytical design sensitivity analysis of the system is used for high accuracy and efficiency. To demonstrate the usefulness of the proposed optimal design program incorporating analysis, design sensitivity analysis, and optimization modules, a damped anisotropic rotor-bearing system is optimized to obtain 34$ weight reduction.

헬리콥터 로터 블레이드의 기본 물리량 및 비회전 동특성 시험 (Basic Properties Test and Non-rotating Dynamic Test of Helicopter Rotor)

  • 윤철용;김태주;기영중;심헌수;김승호
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2013년도 추계학술대회 논문집
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    • pp.103-108
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    • 2013
  • This paper describes basic properties tests and non-rotating dynamic test for rotor blade, flexbeam, and torque tube of which bearingless rotor in helicopter consists. A basic properties test are bending and twist test to find the flap stiffness, lag stiffness, and twist stiffness of specimens. The purpose of dynamic test is to find natural frequencies and modes in non-rotating state. The test results are used to update the analysis model. The updated analysis results using rotorcraft comprehensive code match the tests quite well. The updated model input based on the tests will be utilized to analysis the conditions of rotating whirl tower test before the whirl test and will be compared with the whirl tower test results.

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시일의 마멸이 다단 터빈 펌프 동특성에 미치는 영향 (Effect of Seal Wear on the Rotordynamics of a Multistage Turbine Pump)

  • 김영철;이동환;이봉주
    • 소음진동
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    • 제7권6호
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    • pp.1015-1023
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    • 1997
  • Rotordynamic analysis of a multistage turbine pump using finite element method is performed to investigate the effects of seal wear on its system behavior. Stiffness and damping coefficents of the 2-axial grooved bearing are obtained as functions of rotating speed. Stiffness and damping coefficients of plane annuler seals are calculated as functions of rotating speed as well as seal clearance of seals become larger, these stiffness and damping coefficients decrease drastically so that there can be significant changes in whirl natural frequencies and damping characteristics of the pump rotor system. Although a pump is designed to operate with a sufficient seperation margin from the 1st critical speed, seal wear due to long operation may cause a sudden increase in vibration amplitude by resonance shift and reduce seal damping capability.

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동적 유한요소에 의한 회전축 계의 진동 해석 (Vibration Analysis of Rotor Systems Using Finite Dynamic Elements)

  • 양보석;황형섭
    • 소음진동
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    • 제7권3호
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    • pp.467-475
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    • 1997
  • A rotor-bearing system has been investigated, including internal damping and axial torque using finite dynamic elements. A procedure is presented for dynamic modeling of rotor-bearing system which consist of finite dynamic shaft elements, rigid disk, and bearing and seal. A finite dynamic element model including the effects of rotatory inertia, gyroscopic moments, axial force, and axial torque is developed using the frequency dependent shape function. The natural whirl speeds, stability, and unbalance response of rotor system are calculated on several cases and compared with the conventional finite elements.

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지지구조물을 고려한 로터-베어링 시스템의 동 특성해석 (Dynamic Characteristics Analysis of Rotor-Bearing System with Support Structures)

  • 박성훈;오택열
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 1997년도 추계학술대회 논문집
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    • pp.547-550
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    • 1997
  • The dynamic behavior of rotor-bearing system has been investigated using finite element method. A procedure is presented for dynamic modeling of rotor-bearing system which consist of shaft elements, rigid disk, flexible bearing and support structures. A finite element model including the effects of rotary inertia, shear deformation, gyroscopic moments is developed. Linear stiffness and damping coefficient are calculated for 3 lobe sleeve bearing. The whirl frequency, mode shape, stability and unbalance response of rotor system included effect of bearing coefficient and support structures are calculated.

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유막 저어널 베어링이 회전체에 미치는 진동 특성에 관한 연구 (A Study on the Vibration Characteristics of Rotor System with Fluid Film Bearing)

  • 박성환;오택열
    • 한국정밀공학회지
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    • 제19권10호
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    • pp.37-44
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    • 2002
  • The dynamic behavior of rotor-bearing system has been investigated using finite element method. A procedure is presented for dynamic modeling of rotor-bearing system which consists of shaft elements, rigid disk, flexible bearing and support structure. A finite element model including the effects of rotary inertia, shear deformation, gyroscopic moments is developed. Linear stiffness and damping coefficients are calculated for 2 lobe sleeve bearing. The whirl frequency, mode shape, stability and unbalance response of rotor system including effects of bearing coefficient and support structures are calculated.

터보 냉동기의 변동 기어하중을 고려한 로터다이나믹 해석 Part I : 구동 모터-불기어 로터-베어링 시스템 (Rotordynamic Analysis of a Turbo-Chiller with Varying Gear Loadings Part I ; A Driving Motor-Bull Gear Rotor-Bearing System)

  • 이안성;정진희
    • 소음진동
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    • 제9권3호
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    • pp.593-599
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    • 1999
  • A rotordynamic analysis is performed with a motor-bull gear rotor system supported on two partial bearings, which is intended to drive a high-speed turbo-chiller compressor impeller shaft through its built-in pinion gear. The motor-bull gear rotor system has a rated speed of 3,600 rpm, and is modeled utilizing the finite element method for analysis. As loadings on the bearings due to the gear action are significant in the system considered, each resultant bearing load is calculated statically by considering the generalized forces of the gear action as well as the rotor itself. The two support partial bearings are designed to take their varying loads along with their varying load angles, and they are also analyzed to give their rotordynamic coefficients. Then, a complex rotordynamic analysis of the motor-bull gear rotor-bearing system is carried out to evaluate its whirl natural frequencies and mode shapes and unbalance responses under various loading conditions. Results show that the bearings and entire rotor system are well designed regradless of operating conditions, i.e., loads and operating speeds.

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기어 물림 효과에 의한 횡-비틀림 연성을 갖는 터보-냉동기 로터-베어링 시스템의 동특성 (Dynamic Characteristics of a Turbo-chiller Rotor-Bearing System having a Lateral-Torsional Coupling by Gear Mesh Effect)

  • 이안성;하진웅
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2000년도 춘계학술대회논문집
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    • pp.1034-1039
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    • 2000
  • In turbo-machines operated at high speeds through gear speed increasers a precise coupled analysis of lateral and torsional vibrations is required to achieve highly reliable designs with low vibration and low noise levels, where the vibration coupling is due to the gear pair mesh stiffness. In this paper, applying the generalized coupled lateral-torsional finite element model of a gear pair element, has been analyzed a coupled lateral-torsional vibration of the prototype 800 RT turbo-chiller rotor-bearing system with a bull-pinion gear speed increaser. Results have shown that the coupled torsional natural frequencies have decreased due to the coupling effect of lateral vibration and particularly, the 2nd torsional natural frequency and its mode shape have had big changes. However, changes of lateral vibration characteristics have been noticed only at high lateral whirl natural frequencies above 15,000 rpm.

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고속 운전용 건식진공펌프 로터-베어링 시스템의 회전체동역학 해석 (Rotordynamic Analysis of a Dry Vacuum Pump Rotor-Bearing System for High-Speed Operation)

  • 이안성;이동환;김병옥
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2006년도 추계학술대회논문집
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    • pp.523-530
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    • 2006
  • A rotordynamic analysis was performed with a dry vacuum pump, which is a major equipment in modern semiconductor and LCD manufacturing processes. The system is composed of screw rotors, lobes picking air, helical gears, driving motor, and support rolling element hearings of rotors and motor. The driving motor-screw rotor system has a rated speed of 6,300rpm, and was modeled utilizing a rotordynamic FE method for analysis, which was verified through the results of its 3-D finite element model. As loadings on the bearings due to the gear action were significant in the system considered, each resultant bearing load was calculated determinately and indeterminately by considering the generalized forces of the gear action as veil as the rotor itself. Each resultant hearing loading was used in calculating each stiffness of rolling element bearings. Design goals are to achieve wide separation margins of critical speeds and favorable unbalance responses of the rotor in the operating range. Then, a complex rotordynamic analysis of the system was carried out to evaluate its forward synchronous critical speeds, whirl natural frequencies and mode shapes, and unbalance responses under various unbalance locations. Results show that the entire system is well designed in the operating range. In addition, the procedure of rotordynamic analysis for dry vacuum pump rotor-bearing system was proposed and established.

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산업용 원심분리기의 진동저감을 위한 로터다이나믹 해석 (A Rotordynamic Analysis of a Industrial Centrifuge for Vibration Reduction)

  • 김병옥;이안성
    • 한국소음진동공학회논문집
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    • 제18권8호
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    • pp.879-885
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    • 2008
  • A rotordynamic analysis was performed with a decant-type centrifuge, which is a kind of industrial centrifuge. The system is composed of screw rotor, bowl rotor, driving motors, gear box, and support rolling element bearings. These rotors have a rated speed of 4300 rpm, and were modeled utilizing a rotordynamic FE method for analysis, which was verified through 3-D FE analysis. Design goals are to achieve wide separation margins of lateral critical speeds, and favorable unbalance responses of the rotor in the operating range. Then, a complex analysis rotordynamic analysis of the system was carried out to evaluate its forward synchronous critical speeds and mode shapes, whirl natural frequencies, and unbalance responses under various balance grade. As a result of analysis, the rotordynamic analysis performed by separating a screw rotor and bowl rotor may cause an error in predicting critical speed of entire system. Therefore, the rotordynamic analysis of a coupled rotor combining a screw and bowl rotor must be performed in order to more accurately estimate dynamic characteristics of the decanter-type centrifuge as presented in this paper. Also, rolling element bearings with suitable stiffness should be selected to keep enough separation margin. In addition, in establishing balance grade of a screw and bowl rotor, ISO G2.5 balance grade is more recommended than ISO G6.3, in particular balancing correction of a screw rotor based on ISO G2.5 grade is strongly recommended.