• Title/Summary/Keyword: Critical Speed Map

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Development of Rotordynamic Analytical Model and Analysis of Vibration Response of a Turbocharger (터보차져의 로터다이나믹 해석모델 개발 및 진동응답 해석)

  • Kim, Byung-Ok;Lee, An-Sung
    • The KSFM Journal of Fluid Machinery
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    • v.13 no.5
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    • pp.35-42
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    • 2010
  • This paper deals with the development of analytical model of a turbocharger and its detail rotordynamic analysis. Two analytical models, which are verified by experimental modal testing, are proposed and the analytical model including rotor shaft extended to compressor and turbine wheel end side is chosen. A rotordynamic analysis includes the critical map, Campbell diagram, stability, and unbalance response, especially nonlinear transient response considering nonlinear fluid film force at bearings. Although the linearized analysis accurately predicts the critical speeds, stability limit, and stability threshold speed, the predicted vibration results are not valid for speeds above the stability threshold speed since the rotor vibrates with a subsynchronous component much larger than the one synchronous with rotor speed. Hence, for operating speed above the stability threshold, a nonlinear transient analysis considering nonlinear fluid film force must be performed in order to accurately predict vibration responses of rotor and guarantee results of analysis.

Analysis of Dynamic Characteristics of Water Injection Pump (물 분사 펌프의 동특성 분석)

  • Lee, Jong Myeong;Lee, Jeong Hoon;Ha, Jeong Min;Ahn, Byung Hyun;Kim, Won Cheol;Choi, Byeong Keun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.12
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    • pp.1483-1487
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    • 2013
  • Water injection pump outputs oil with high pressure during this process, seawater is injected into the well to recover the well pressure and maintain high productivity. A water injection pump has high productivity, and therefore, it serves as a key piece of equipment in marine plants. In this light, water injection pumps are being studied widely in industry. In this study, the rotor dynamics is analyzed to determine the natural frequency according to the bearing stiffness and operation speed change. This study aims to establish the pump reliability through critical speed, stability, and unbalance response analysis.

Development of Analysis Program of Dynamic Characteristic for the Propulsion Shafting System (선박추진축계 동특성 분석 프로그램 개발)

  • Ha, Jeong-Min;Lee, Jeong-Myeong;Lee, Jeong-Hoon;Kim, Yong-Whi;Ahn, Byeong-Hyun;Choi, Byeong-Keun;Kim, Won-Chul
    • Journal of Power System Engineering
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    • v.18 no.2
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    • pp.57-61
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    • 2014
  • Due to the changes of marine transportation industry, it requires ship in larger scale and high speed. In order to operate efficiently, the engine should be work in high power and high horse power. The increase of the number of the propeller blades and the pitch of the screw and the weight, vibration of shafting problems occurs. To evaluate the safety of the system through analyzing the dynamic characteristics propulsion shafting system, was used to prove or to verify the Lalanne & Ferraris model validation.. It indicates that the Program through Campbell diagram and Critical speed map, Root rocus map, to ensure the reliability of the experimental model.

A Rotordynamic and Stability Analysis of Process Gas Turbo-Compressor in accordance with API 617 Standard (API 617 규격에 의거한 프로세스 가스 터보압축기의 로터다이나믹 해석 및 안정성 검토)

  • Kim, Byung-Ok;Lee, An-Sung
    • The KSFM Journal of Fluid Machinery
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    • v.12 no.5
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    • pp.47-53
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    • 2009
  • A rotordynamic and detailed stability analysis in accordance with API 617 standard were performed with a turbo-compressor, which is one of key rotating machinery in refinery, petroleum, and power plants. The system is composed of rotor shaft, impeller, sleeve hub, balance drum, and coupling hub. The rotor system is supported by tilting pad bearings, which has 5 pads and pad on loading condition. The rotordynamic analysis specified by API 617 includes the critical speed map, mode shape analysis, Campbell diagram, unbalance response analysis, and stability analysis. In particular, the specifications of stability analysis consist of a Level 1 analysis that approximates the destabilizing effects of the labyrinth seals and aerodynamic excitations, and Level 2 analysis that includes a detailed labyrinth seal aerodynamic analysis. The results of a rotordynamic analysis and stability analysis can evaluate the operating compressor health and can be utilized as a guide of its maintenance, repair and trouble solution.

Design of A two-stage Compressor Supported by Air-lubricated Multi-leaf Foil Journal Bearings (공기윤활 다엽포일 제어널 베어링으로 지지된 이단 압축기의 설계)

  • 김태호;이용복;김창호;이남수;김한길
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.05a
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    • pp.936-941
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    • 2001
  • This paper deals with the design of oil-tree motor-driven two-stage centrifugal compressor supported by air-lubricated multi-leaf foil bearings. The design of this compressor is performed, based upon prediction of critical speeds, load capacity, and stability. It is demonstrated in this paper that multi-leaf foil bearings can be adopted to satisfactorily support this centrifugal compressor.

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Modal Analysis of the Switched Reluctance Motor Using 3D Transfer Matrix Method (3차원 전달행렬법을 이용한 스위치드 릴럭턴스 전동기의 모달 해석)

  • Ha, K.H.;Kang, K.H.;Hong, J.P.;Kim, G.T.
    • Proceedings of the KIEE Conference
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    • 1999.07a
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    • pp.173-175
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    • 1999
  • This paper deals with the rotor vibration analysis of Switched Reluctance Motor(SRM) with the 6/4 poles. For this analysis, 3-dimensional mode shapes corresponding to the natural frequency and critical speed map according to rotor speed are presented by using 3D Transfer Matrix Method(TMM). The gyroscopic effect and shear deformation of rotor are considered.

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A Study on Driver Perception-Reaction Time in High-Speed Driving Situations (고속주행상황의 운전자 인지·반응시간에 관한 연구)

  • Choi, Jaisung;Jeong, Seungwon;Kim, Jeongmin;Kim, Taeho;Shin, Joonsoo
    • International Journal of Highway Engineering
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    • v.19 no.1
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    • pp.107-119
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    • 2017
  • PURPOSES : The desire of drivers to increase their driving speeds is increasing in response to the technological advancements in vehicles and roads. Therefore, studies are being conducted to increase the maximum design speed in Korea to 140 km/h. The stopping sight distance (SSD) is an important criterion for acquiring sustained road safety in road design. Moreover, although the perception-reaction time (PRT) is a critical variable in the calculation of the SSD, there are not many current studies on PRT. Prior to increasing the design speed, it is necessary to confirm whether the domestic PRT standard (2.5 s) is applicable to high-speed driving. Thus, in this study, we have investigated the influence of high-speed driving on PRT. METHODS : A driving simulator was used to record the PRT of drivers. A virtual driving map was composed using UC-Win/Road software. Experiments were carried out at speeds of 100, 120, and 140 km/h while assuming the following three driving scenarios according to driver expectation: Expected, Unexpected, and Surprised. Lastly, we analyzed the gaze position of the driver as they drove in the simulated environment using Smarteye. RESULTS : Driving simulator experimental results showed that the PRT of drivers decreased as driving speed increased from 100 km/h to 140 km/h. Furthermore, the gaze position analysis results demonstrated that the decrease in PRT of drivers as the driving speed increased was directly related to their level of concentration. CONCLUSIONS : In the experimental results, 85% of drivers responded within 2.0 s at a driving speed of 140 km/h. Thus, the results obtained here verify that the current domestic standard of 2.5 s can be applied in the highways designated to have 140 km/h maximum speed.

Study on the Air Foil Bearings of the Turbo-Expander for Fuel Cell System (연료 전지용 터보 익스펜더의 공기 포일 베어링에 대한 연구)

  • Lee Yong-Bok;Park Dong-Jin;Kim Chang-Ho
    • Tribology and Lubricants
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    • v.21 no.3
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    • pp.114-121
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    • 2005
  • As fuel cell system is environmental friendly generator, its performance depends on its air supply system. Because, fuel cell stack generates electrical energy by electron and the electron is generated by reacting between air and hydrogen. So, more and more compressed air is supplied, more and more the energy can be obtained. In this study, turbo-expander supported by air foil bearing is introduced as the air supply system used by fuel cell systems. The turbo-expander is a turbo machine which operates at high speed, so air foil bearings suit its purpose for the bearing elements. Analysis for confirming the stability and endurance is conducted. Based on FDM and Newton-Raphson method, characteristics of air foil bearing, dynamic coefficients, pressure field and load capacity, are obtained. Using the characteristics of air foil bearing, the rotordynamic analysis is performed by finite element method. The analysis (stability analysis and critical speed map) shows that turbo-expander is stability at running speed. After the analysis, the test process and results are presented. The goals of test are running up to 90,000 RPM, flow rate of 150 $m^3/h$ and pressure ratio of 1.15. The test results show that the aerodynamic performance and stability of turbo-expander are satisfied to the primary goals.

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
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    • 2014.04a
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    • pp.408-414
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    • 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.

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Delay Optimization Algorithm for the High Speed Operation of FPGAs (FPGA를 고속으로 동작시키기 위한 지연시간 최적화 알고리듬)

  • Choi, Ick-Sung;Lee, Jeong-Hee;Lee, Bhum-Cheol;Kim, Nam-U
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.37 no.7
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    • pp.50-57
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    • 2000
  • We propose a logic synthesis algorithm for the design of FPGAs operating at high speed. FPGA is a novel technology that provides programmability in the field. Because of short turnaround time and low manufacturing cost, FPGA has been noticed as an ideal device for system prototyping. Despite these merits, FPGA has drawbacks, namely low integration and long delay time comparing to ASIC. The proposed algorithm partitions a given circuit into subcircuits utilizing a kernel divisor such that the subcircuits can be performed at the same time, hence reducing the delay of the circuit. Experimental results on the MCNC benchmark show that the proposed algorithm is effective by generating circuits having 19.1% les delay on average, when compared to the FlowMap algorithm.

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