• Title/Summary/Keyword: vibration, unbalance

Search Result 311, Processing Time 0.023 seconds

Study on the prevention of spragging in a tilting pad journal bearing using the variation of preload (예압 변경을 통한 틸팅패드 저널베어링의 Spragging 방지에 관한 연구)

  • Yang, Seong-Heon;Park, Chul-Hyun;Ha, Hyun-Cheon;Kim, Chae-Sil
    • Proceedings of the KSME Conference
    • /
    • 2001.06c
    • /
    • pp.281-286
    • /
    • 2001
  • Tilting pad journal bearings have been widely used in a high speed rotating machinery, such as steam turbines and gas turbines, owing to their inherent stability characteristics. However, some peculiar fatigue failure in the babbitt metal due to spragging has been continuously occurred at the leading edge of the upper pads. The spragging is defined as the pad vibration initiated on the upper unloaded pads in a tilting pad journal bearing. This paper describes both several kinds of bearing failure related with spragging and the theoretical investigation on the prevention of the spragging phenomenon using the variation of preload. Results show that positive preload(m>0.5) assures all pads remain statically loaded under all operating conditions. For the change of design parameter to prevent spragging, thermo-hydrodynamic lubrication and rotor dynamic analysis were performed to verify temperature limitation on bearing and vibration problems on rotor bearing system.

  • PDF

Study on the Prevention of Pad Fluttering with the Variation of Preload in a Tilting Pad Journal Bearing (예압 변경을 통한 틸팅패드 저널베어링의 패드 Fluttering 방지에 관한 연구)

  • 박철현;김재실;하현천;양승헌
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.14 no.4
    • /
    • pp.344-351
    • /
    • 2004
  • Tilling pad journal bearings have been widely used to support the rotors of the high rotating machinery such as steam and gas turbines owing to their inherent dynamic stability characteristics. However, serious bearing problems such as fatigue damage in the upper unloaded pad, the break of locking pins and the wear of pinholes etc. by pad fluttering are frequently taken place in the actual steam turbines. The purpose of this paper is to investigate the mechanism of pad fluttering and to suggest the useful design guideline(application of preload, m) for the purpose of preventing bearing problems by pad fluttering in a tilting pad journal bearing. It is estimated that upper pad is easy to flutter because the film shape of the upper pad is diverged by moment acting on pivot point. This paper suggests that effective preload range(m $\geq$ 0.5) in order to be statically loaded pad under all operating conditions. Also, design modified bearing is suggested for the adjustment in actual steam turbines. And bearing and rotor dynamic analysis are performed to identify bearing characteristics and to verify the reliability of rotor-bearing system.

Development of High Speed Spindle for Machine Tool with Magnetic Bearings (자기베어링 적용 공작기계용 고속 스핀들 개발)

  • Park, Cheol Hoon;Ham, Sang Yong;Hong, Doo Euy;Kim, Jun Kyu
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.25 no.12
    • /
    • pp.895-900
    • /
    • 2015
  • Most of spindles for machine tool are supported by ball bearings, and there are problems in the limits of high speed and high power as well as the cumbersome maintenance due to the short life time. In order to overcome these problems of the conventional spindles, the high speed spindle with magnetic bearings is developed in this study. Magnetic bearings for 60 000 r/min class high-speed spindle are designed, and high speed spindle with magnetic bearings are fabricated. Based on the running test up to 60 000 r/min, it is verified that the spindle is stably supported by the magnetic bearings, and the magnitude of the unbalance response at 60 000 r/min is less than $3{\mu}m$.

Analysis of dynamics characteristics of water injection pump through the 2D finite element (2D 유한요소 해석을 통한 Water injection pump의 동특성 분석)

  • LEE, JONG-MYEONG;KIM, YONG-HWI;KIM, JUN-HO;CHOI, HYEON-CHEOL;CHOI, BYEONG KEUN
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2014.04a
    • /
    • pp.408-414
    • /
    • 2014
  • After drilling operations at the offshore plant to production to crude oil to high pressure. After that time the low pressured of pipe inside when the secondary produce so oil recovery is reduced. At that time injection sea water at the pipe inside through water injection pump that the device Increase recovery so to be research and development at many industry. So developing 3-stage water injection pump at the domestic company. A variety of mathematical analysis during the detailed design analysis was not made through the dynamics characteristic. In this paper, a 2D finite element analysis is performed through the dynamics of the present study was the validation of the model.

  • PDF

Dynamic Characteristics of a Coupled Journal and Thrust Hydrodynamic Bearing in a HDD Spindle System Due to Groove Location (HDD 스핀들 시스템에 사용되는 저널과 트러스트가 결합된 유체 동압 베어링의 홈 위치에 따른 동특성 해석)

  • 윤진욱;장건희
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2001.11a
    • /
    • pp.304-311
    • /
    • 2001
  • This research numerically analyzes the dynamic characteristics of a coupled journal and thrust hydrodynamic bearing due to its groove location which has the static load due to the weight of a rotor in the axial direction and the dynamic load due to its mass unbalance in the radial direction. The Reynolds equation is transformed to solve a plain member rotating type of journal bearing(PMRJ), a grooved member rotating type of journal bearing (GMRJ), a plain member rotating type of thrust bearing (PMRT) and a grooved member rotating type of thrust bearing (GMRT). FEM is used to solve the Reynolds equations in order to calculate the pressure distribution in a fluid film. Reaction forces and friction torque are obtained by integrating the pressure and shear stress along the fluid film, respectively. Dynamic behaviors, such as whirl radius or floating height of a rotor, are determined by solving its nonlinear equations of motion with the Runge-Kutta method. This research shows that the groove location affects the pressure distribution in the fluid film and consequently the dynamic performance of a HDD spindle system.

  • PDF

Development of the Multi-Gear Train Devices of Synchro System for the Guns of a Warship which Considered the Noise/Vibration (소음/진동을 고려한 함포용 Synchro System의 다단 기어 구동장치 개발)

  • Lee, Hyoung-Woo;Hur, Nam-Soo;Kim, In-Hwan;Lee, Dong-Hwan
    • Journal of Advanced Marine Engineering and Technology
    • /
    • v.34 no.8
    • /
    • pp.1057-1067
    • /
    • 2010
  • Vibration and noise analysis as well as strength of gear teeth, gear profile design are considered in order to develop the multi-gear train devices of synchro system for the guns of a warship. A new approach to the critical speed calculation of practical industrial multi-mesh geared system is presented. A transfer matrix model based on Hibner's branch method is developed and the natural properties of the branched rotor system are calculated with using the ${\lambda}$-matrix formulation. A Campbell diagram, in which the excitation sources caused by the mass unbalance of the rotors and the transmitted errors of the gearing are considered, shows that, at theoperating speed, there are not the critical speed.

Evaluation of Rotor Dynamic Characteristic of Roots Type Vacuum Pump (루츠타입 진공펌프의 동특성 평가)

  • Lee, Jong-Myeong;Kim, Yong-Hwi;Ha, Jeong-Min;Gu, Dong-Sik;Hwang, Ho-Jun;Choi, Byeong-Keun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2011.10a
    • /
    • pp.264-270
    • /
    • 2011
  • The goal of this study is a stability evaluation through eigenvalue and rotor dynamics analysis of the vacuum pump. The vacuum pump used is a roots type pump, one of the dry middle vacuum pumps, is necessary at the procedure to produce semiconductor and display. The eigenvalue evaluation is solved by numerical analysis through using Modal test and 2D 3D models. Both the experiment and the analysis result are similar, the analysis result using 2D is more oculate the 3D model comparing with test result. So rotor dynamic evaluation is performed through using 2D model. Rotor dynamic evaluation used the campbell diagram and root locus map which were acquired by complex eigenvalue analysis. And we checked minimum clearance of vacuum pump composition between two rotors through unbalance response analysis. Thus, vacuum pump, the target object of this study, was evaluated to be operated stably.

  • PDF

Study on the Mechanism of pad Fluttering and the Prevention of pad Fluttering with the Variation of Preload in a Tilting Pad Journal Bearing (틸팅패드 저널베어링의 패드 fluttering 메커니즘 및 예압 변경을 통한 패드 fluttering 방지에 관한 연구)

  • 박철현;김재실;하현천;양승헌
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2003.11a
    • /
    • pp.291-297
    • /
    • 2003
  • Fluid film tilting pad journal bearings are widely used for large steam turbines. However, bearing problems by pad fluttering, such as fatigue damage in the upper unloaded pad, the break of locking pins and the wear of pinholes etc., are frequently taken place in the actual steam turbines. The purpose of the present work is to investigate on the mechanism of pad fluttering and the prevention of pad fluttering with the variation of preload(m) in a tilting pad journal bearing. It is estimated that upper pad is easy to flutter because the film shape of upper pad is diverged one from the analysis of moment direction acting on pivot point. Effective preload range in order to be statically loaded pad under all operating conditions is suggested as m>0.5. Also, as a bearing that can be prevented pad fluttering, design modified bearing is suggested. For the adjustment in actual steam turbines, bearing and rotor dynamic analysis are performed to identify bearing characteristics and to verify the reliability of rotor-bearing system.

  • PDF

A Study on the Identifying Dynamic Characteristic Parameters of Rotor-bearing Systems Using Field Measurement Data of Unbalance Responses (현장 불평형 응답에 의한 로터-베어링 시스템 매개변수 규명에 관한 연구)

  • 이동환;박노길;김영일;이형우
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.14 no.8
    • /
    • pp.684-694
    • /
    • 2004
  • Presented in this dissertation is a new method of identifying the critical speed of rotor-bearing systems without actually reaching at the critical speed itself. Using the method, it is possible to calculate the critical speed by measuring a series of rotor responses at much lower rotating speeds away from and without reaching at the critical speed of the system. In the course of the procedures illustrated, not only the critical speed but also the damping ratio and the eccentricity of the system can be identified at the same time. Test rotor was tested on the Rotor Dynamics Test Facility at the Korea Institute of Machinery & Materials. Korea, and the theory has been confirmed experimentally. The method can be adopted to monitor changes of the dynamic characteristics of critical rotating machinery before and after overhauls, repairs, exchanges of various parts, or to detect trends or direction of subtle changes in the dynamic characteristic parameters over a long periods of time.

Experimental Study on Noise Reduction of Fan for Automotive Air Conditioner (차량용 공조 팬의 소음 저감에 대한 실험적 연구)

  • Lee, Jin-Kab;Chung, Byung-Hoon
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.14 no.1
    • /
    • pp.51-56
    • /
    • 2013
  • This paper is the experimental study to investigate the noise sources location in order to reduce the noise level of line flow fan for the air conditioner in the subway car. The noise of line flow fan is caused by various factors such as the turbulence by air flow, random noise, noise of blade passing frequence(681Hz) and noise due to structural vibration of rotor unbalance(28.4Hz) by motor revolution. By performing the noise reduction on each sound source, the noise level is decreased as much as 5.7dB(A) through the controls of housing guide angle and distance, the configuration changes of flow passage shape and rotor balancing.