• Title/Summary/Keyword: Combustion Vibration

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Vibration Transmissibility Analysis and Measurement of Automotive Clutch Spring Dampers (차량 클러치 스프링 댐퍼의 진동 전달률 해석 및 측정)

  • Jang, Jae-Duk;Kim, Gi-Woo;Kim, Won-Jin
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.23 no.10
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    • pp.902-908
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    • 2013
  • The input torque ripple induced by combustion engines is a significant source of NVH(noise, vibration and harshness) problem in automotive transmissions. Because this torque fluctuation is primarily transmitted to the input shaft of automotive powertrains(e.g., automatic transmissions) when the lock-up clutches are closed, a torsional damper with helical springs is generally inserted between engine and transmissions to isolate the input vibratory energy, which is essential for the passenger comfort. The torsional vibration isolator exhibits frequency ranges in which there is low vibration transmissibility. However, the isolation performance is currently evaluated through the static torsional spring characteristics. In this study, the transmissibility of torsional spring dampers, essential dynamic performance index for vibration isolator, is first experimentally evaluated.

The Transfer Matrix Method for Three-Dimensional Vibration Analysis of Crank Shaft (전달행렬법을 사용한 크랭크축의 3차원 진동해석)

  • 이정윤;오재응
    • Transactions of the Korean Society of Automotive Engineers
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    • v.5 no.4
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    • pp.152-159
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    • 1997
  • This paper presents a vibration analysis method of crank shaft of six cylinder internal combustion engine. For simple analysis journal, pin and arm parts were assumed to have uniform section. Transfer Matrix Method was used, considering branched part and coordinate transformation part. Natural frequencies, modeshapes and transfer functions of crank shaft were investigated based upon the Euler beam theory: It was shown that the calculated natural frequencies, modeshapes agree well with the existing paper results.

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The Study for Improving the Combustion in a D.I. Diesel Engine using Multi-cavity Piston (Multi-cavity Piston에 의한 디젤기관의 연소성 향상에 관한 연구)

  • Park, Chul Hwan;Bang, Joong Cheol
    • Journal of the Korean Society of Combustion
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    • v.20 no.3
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    • pp.13-20
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    • 2015
  • The performance of a direct-injection diesel engine often depends on the strength of swirl or squish, the shape of combustion chamber, the number of nozzle holes, etc. This is natural because the combustion in the cylinder was affected by the mixture formation process. Since the available duration to make the mixture formation of air-fuel is very short, it is difficult to make complete mixture. Therefore, an early stage of combustion is violent, which leads to the weakness of noise and vibration. In this paper, the combustion process of a common-rail diesel engine was studied by employing two kinds of pistons. One has several cavities on the piston crown to intensify the squish during the compression stroke in order to improve the atomization of fuel, we call this multi cavity piston in this paper. The other is a toroidal single cavity piston, generally used in high speed diesel engines. To take photographs of flame and flaming duration, a four-stroke diesel engine was remodeled into a two-stroke visible single cylinder engine and a high speed video camera was used.

Analysis and Prediction of Structural Vibration for Diesel Engine Generator Set (디젤 발전기세트의 구조진동특성 연구)

  • 이수목;김관영;김원현
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.05a
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    • pp.948-954
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    • 2002
  • The structural vibration of a diesel generator set was investigated through analyses and tests. FE modeling and normal mode analysis were performed and compared with measured results for both structure components and generator set assembly. The results of component analyses were fairly well coincident with measured results but those of assembled generator set showed more or less discrepancies. Discussions were given about the uncertainties for vibration characteristics of component structures and assembled running structures especially concerning their nonlinearities and damping effects. Detailed excitation analysis fellowed by forced response analysis was done from the engine and pressure data to compare with the actual measured vibration. As results the vibration prediction for frame structures of reciprocating internal combustion engine was confirmed reliable to some extent.

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Torsional Vibration Stress Analysis for Shafting in Reciprocating Machine by Transfer Stiffness Coefficient Method (전달강성계수법에 의한 왕복 기계 축계의 비틀림진동 응력해석)

  • 최명수
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.14 no.8
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    • pp.749-756
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    • 2004
  • While designing shafting in reciprocating machines with internal combustion engines which derive generators, pumps, and vehicles, it is very important to calculate the additional stress of shafting by torsional vibration. In this paper, the transfer stiffness coefficient method which is based on the successive transfer of stiffness coefficient was applied to the calculation of the additional stress of shafting in reciprocating machine by torsional vibration. In order to confirm the effectiveness of the present method, a propulsion shafting with a diesel engine in a vessel was considered as the computational example of shafting in reciprocating machine. The results calculated by the present method were compared with those of the modal analysis method, the mechanical impedance method, and free vibration analysis.

Vibration Control of Engine Body for Two Stroke Low Speed Diesel Engine using Dynamic Vibration Absorber (동흡진기에 의한 저속 2행정 디젤엔진의 본체진동 제어)

  • 이돈출;유정대;김정렬
    • Journal of Advanced Marine Engineering and Technology
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    • v.26 no.6
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    • pp.631-637
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    • 2002
  • Two stroke low speed diesel engines are used as a power supplier not only for marine vessel but also diesel power plant with a benefit of its higher mobility and durability than the other thermal engines. However, there are some disadvantages such as the bigger vibrating excitation forces generated by high combustion pressure in cylinders which various kinds of vibrations are caused. In this paper, it is theoretically studied to control engine body vibration using dynamic vibration absorber. As an actual case, dynamic absorbers are designed for controlling X-mode vibration of 9K80MC-S engine on the diesel power plant and its performance is identified by the vibration test both in shop and site

A Study on the combustion characteristcs for backpressure of exhaust system in SI engine (배기(排氣)시스템의 배압(背壓)과 연소특성(燃燒特性)에 관한 연구)

  • Park, Dai-Un;Park, Kyoung-Suk;Park, Se-Jong;Son, Sung-Man
    • 한국연소학회:학술대회논문집
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    • 2004.11a
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    • pp.206-212
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    • 2004
  • It is necessary to consider the stability, economic environmental-friendly problems by the development of the road, supply of the automobile, environmental problem as designing the exhaust system. To reduce the noise and the vibration of the automobile, it is needed to consider the pulsation noise, air current noise, vibration of air pipe which generate the intake and exhaust noise of the automobile. Moreover, the discharge sounds, intake sound, radiation sound, transmitted sound are occurred. To reduce this influence, the variable valve is needed and to control these factors, path transformation muffler and active type muffler are needed. While engine efficiency could be reduced with this transformationand resistance by the pressure, thermal property. In this study, how to design exhaust systems yielding higher condversion efficiency, lower backpressure and optimize the performance. this study is recommended for exhaust system and designers and engineers involved in SI engine exhaust system and it will furnish information for you to design more efficient.

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Design and Application of Emergency Blockage System for Engine Part at IPPT and SQT (IPPT, SQT에서의 엔진부 비상정지 시스템 설계 및 운용)

  • 하성업;이중엽;정태규;한상엽
    • Journal of the Korean Society of Propulsion Engineers
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    • v.7 no.2
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    • pp.44-53
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    • 2003
  • A vertical hot-firing test facility was established to carry out the IPPT(Integrated Propulsion Performance Test) and SQT(Stage Qualification Test) of KSR-III(Korea Sounding Rocket-III). The components for actual launcher were mostly used, hence these tests were carried out under the condition of relatively lower safety margin. To perform hot-firing tests with the maximum safety, an engine emergency blockage system was investigated and applied. An emergency blockage system using combustion chamber pressures and acceleration signals was set up to monitor ignition delay and fail, flame out, propellant feeding status, unstable combustion and excessive structural vibration. With such a system, the test safety could be secured by rapid judgement and follow-up measures, which made IPPT and SQT be safely completed.

FFT based Monitoring System for Combustion Vibration Data Processing of Gas Turbine (가스터빈 연소진동 데이터 처리를 위한 FFT 기반의 모니터링 시스템)

  • Lee, Sang-Hyeok;Kang, Feel-Soon
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.11 no.12
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    • pp.2327-2334
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    • 2007
  • This paper presents a method for improvement of communication speed and reduction of data storage space in gas turbine monitoring system to acquire, save, and display combustion vibration data. The proposed method implements FFT from sampled raw data. The FFT result data are encoded to be transferred to monitoring PC for storage. By this way, it can reduce data storage space. To display the received data, it needs inverse FFT to reconstruct original signal. To verify the validity and efficiency of the proposed scheme, computer-aided simulation are carried out. It includes the analyzed results the relationship between FFT's order and Gibb's Phenomenon. Finally, high-performance of the proposed method is proved by combustion experiment results using a prototype gas turbine.

Vibration analysis of a DWT 1,000-ton ocean-research vessel with electric propulsion

  • Bae, Dong-Myung;Cao, Bo;Chen, Tuo-Han
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.50 no.1
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    • pp.75-82
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    • 2014
  • In vibration analysis of ships, the principle aim is to determine the natural frequencies and excitation frequencies, and use this information to avoid resonances and vibration damage. The simplest method is to prevent resonance conditions, which is effective as long as the natural frequencies and excitation frequencies can be regarded as independent from environmental conditions. For ships that use electric propulsion systems, the sources of vibration are reduced compared with those caused by a diesel engine or other combustion-based propulsion systems. However, the frequency spectrum of these vibrations may be different; therefore, to understand the characteristics of the electric propulsion, we also should investigate how the ship responds to these vibrations. We focused on a 1,000-ton deadweight (DWT) ocean-research vessel using an electric propulsion system and analyzed the response to vibration.