• Title/Summary/Keyword: Rotor Unbalance

Search Result 221, Processing Time 0.023 seconds

A Study on the Dynamic Characteristics of Truncated Cone Type Squeeze Film Damper Bearing and Rotor System (절단 원추형 Squeeze Film Damper 베어링과 회전축계의 동특성에 관한 연구)

  • 윤석철
    • Journal of the Korean Society of Safety
    • /
    • v.12 no.1
    • /
    • pp.9-18
    • /
    • 1997
  • This paper is a study on the dynamic characteristics of truncated cone type squeeze film damper(SFD) bearing and rotor system. This model can alter the radial oil film gap which Is Important to the performance of rotor-bearing system and manufactured easily to change the shape concept of traditional circular type SFD bearing. In theoretical analysis, the oil film pressure distribution, the oil film force, the film damping coefficient and the eccentricity ratio, etc. were induced with regard to the film inertia effect. The film damping coefficients and optimum design parameters are calculated. When unbalance parameter U is greater than 0.2, the nonlinear vibration such as "Jump" phenomena appears in the vicinity of rotor critical speed. At this time, the increases of bearing parameter U, journal distance S, Reynolds number Re can control this unstable vibration. The experimental results show that SFD hearing and rotor system which are designed according to the design parameters in the stable region are operated stably in rotational speed 9,600rpm without nonsynchronous behavior.

  • PDF

Dynamic Analysis of Rotary Compressor with Rotor Misaligment (축어긋남을 갖는 로터리 컴프레서의 동적해석)

  • 정의봉;김태학
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 1997.10a
    • /
    • pp.82-87
    • /
    • 1997
  • Large dynamic loads act on the rotor in rotary compressors. There are unbalance forces due to eccentric 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 coefficients of the lubricating oil film are not constant in the bearings. The system is considered as a coupled problem of flexible rotor and the journal bearings. Bearing reaction force is calculated from pressure of oil film using Reynolds equations in journal bearings. Pressure distribution in journal bearing is analyzed by finite difference method. The dynamic response of rotor and bearing characteristic are discussed when rotary compressor has a relative misalignment.

  • PDF

Noise Estimation of Oil Lubricated Journal Bearings (유체 윤활 저널 베어링의 소음 예측)

  • Rho, Byoung-Hoo;Kim, Kyung-Woong
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.27 no.7
    • /
    • pp.1058-1064
    • /
    • 2003
  • Noise estimating procedures of oil lubricated journal bearings are presented. Nonlinear analysis of rotor-bearing system including unbalance mass of the rotor is performed in order to obtain acoustical properties of the bearing. Acoustical properties of the bearing are investigated through frequency analysis of the pressure fluctuation of the fluid film calculated from the nonlinear analysis. Noise estimating procedures presented in this paper could aid in the evaluation and understanding of acoustical properties of oil lubricated journal bearings.

Vibration Control of a Sealed and Pressurized Squeeze Film Damper Supported Rotor (가압 밀봉된 스퀴즈 필름 댐퍼로 지지된 로터의 진동제어)

  • 고영호;이건복;김창호
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 1995.10a
    • /
    • pp.589-593
    • /
    • 1995
  • The vibration of rotors in high speed sometimes leads to system failure or reduces the system life, and has a direct connection with stability. In this paper, the system's modelling was conducted in experimentally and the controller was designed to reduce the vibration due to the rotor unbalance using Squeeze Film Damper(SFD). SFD vibration control was achieved in constant rotating speed based on the controller designed. the control was confirmed working quite well in terms of both numerical simulation and experiment.

  • PDF

Rotordynamic Characteristics of High Pressure Multistage Pump (고압 다단펌프 축계 진동 특성 고찰)

  • Song, Ae Hee;Song, Jin Dae;Lim, Woo Seop;Yang, Bo Suk
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2012.10a
    • /
    • pp.592-596
    • /
    • 2012
  • This paper presents numerical analysis result of rotor-bearing system of a multi-stage high pressure pump. Especially resonance possibility, stability and damping factor are estimated for a selected commercial multi-stage high pressure pump. The result shows that it is not easy to avoid resonance of rotor-bearing system against main excitation forces which are residual unbalance force and pressure pulsation. This makes damping effect be more important.

  • PDF

Study on the replacement of last moving blade at lower pressure turbine (저압 터빈 마지막 단 동익 교체에 대한 고찰)

  • Koo, Jae-Raeyang;Lee, Woo-Kwang;Koo, Woo-Sik;Kim, Yeon-Hwan
    • Proceedings of the KSME Conference
    • /
    • 2003.04a
    • /
    • pp.834-838
    • /
    • 2003
  • Vibration of turbine is concerned with array of last moving blade at lower pressure turbine. When last moving blade at lower pressure turbine was replaced, we must consider mass unbalance problems of blades. If mass unbalance happened at rotor, it is impossible to operate turbine. In this paper, we have how to minimize the mass unbalance problems of last moving blade at lower pressure turbine.

  • PDF

A Study on the Active Balancing for High-Speed Rotors (I): Development of the Active Balancing System (고속 회전체의 능동 밸런싱에 관한 연구 (I): 능동 밸런싱 장치의 개발)

  • Kim, Jong-Soo;Park, Hyun-Kyu;Lee, Soo-Hun
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.19 no.4
    • /
    • pp.140-146
    • /
    • 2002
  • High speed rotating machines can be very sensitive to rotating mass unbalance that is a major source of harmful vibration for many types of rotating machinery. So, the balancing procedure is needed for all high-speed rotating system. To save the time and cost of off-line balancing, many researchers have developed the on-line balancing devices and methods. In this paper, an active balancing device, which is an electro-magnetic type, is developed and the active balancing algorithm using influence coefficient method is also proposed. The active balancing experiment for flexible rotors during operation is performed by an active balancing device. As a result, controlled unbalance responses are below the vibration limit at all rotating speed ranges with critical speed.

Model Validation and Controller Design for Vibration Suppression of Flexible Rotor Using AMB

  • Soo Jeon;Ahn, Hyeong-Joon;Han, Dong-Chul
    • Journal of Mechanical Science and Technology
    • /
    • v.16 no.12
    • /
    • pp.1583-1593
    • /
    • 2002
  • This paper discusses the model validation and vibration suppression of an AMB flexible rotor via additional LQG controller. The main difficulty in the vibration suppression of the flexible rotor using AMB is to realize a controller that can minimize resonance without injuring the stabilized rigid modes. In order to solve this problem, simple scheme for system modeling and controller design are developed. Firstly, the AMB flexible rotor is stabilized with a PID controller, which leads to a new stable rotor-bearing system. Then, authors propose the model validation procedure using measured open-loop frequency responses to obtain an accurate model of the AMB flexible rotor system. After that, LQG controller with modal weighting is designed to suppress resonances of the stable rotor-bearing system. Due to the poor controllability and observability of flexible modes compared to rigid ones, balancing of two Gramians is prerequisite for the fair LQG controller design. Simulation with step disturbance and experimental results of unbalance response up to 10,000 rpm verified the effectiveness of the proposed scheme.

A Parametric Study and an Optimal Design of an ER-SFD Supporting a Rigid Rotor System (강성 회전축계를 지지한 ER-SFD의 parametric study 및 최적설계)

  • 김종립;이남수;이용복;김창호;최동훈
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
    • /
    • 1999.06a
    • /
    • pp.279-284
    • /
    • 1999
  • This paper presents a parametric study and an optimal design of the ER-SFD supporting a rigid rotor system. An attempt is made to obtain the optimal design of an ER-SFD for a two degree-of-freedom rotor model. Such a simple model is used in order to get a better insight into the physics of the problem, A maximum whirl amplitude, supply pressure and voltage are considered, and a maximum whirl amplitude is minimized over a range of speeds and presented for some values of unbalance mass. The results presented in this paper provide important design information necessary to reduce a whirl amplitude of an ER-SFD.

  • PDF

Development of Lorentz Force Type Integrated Motor-Bearing System in Dual Rotor Disk Configuration (두 장의 원판형 회전자를 갖는 로렌츠형 자기 베어링 내장 전동기의 개발)

  • Park, Sung-Ho;Lee, Chong-Won
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2005.05a
    • /
    • pp.935-940
    • /
    • 2005
  • In this paper, dual rotor disk configuration with a coreless stator is proposed for the Lorentz force type integrated motor bearing system. An experimental compensation for the effects of high order harmonics is performed using the digital controller of the experimental setup. The runout profile and rotor unbalance are also identified by the extended influence coefficient method. The experimental results confirm that this compensation method effectively attenuates the rotor vibration all over the operating range of rotational speed.

  • PDF