• Title, Summary, Keyword: Engine Noise

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A Study of the Noise Reflection Effect of an Alternator in a 13-liter Turbo-intercooler Diesel Engine (13 리터급 터보.인터쿨러 디젤 엔진의 얼터네이터 소음 반사 효과에 관한 연구)

  • 최성배
    • Journal of Advanced Marine Engineering and Technology
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    • v.27 no.3
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    • pp.381-387
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    • 2003
  • Engine noise consists of the noise radiated from an engine structure and noises from engine ancillaries such as a turbocharger fuel injection system, and alternator. The noise of these ancillaries might be incorrectly evaluated in the aspect of the noise contribution to engine noise because the noise reflection effect of their neighbor engine structure is easily ignored. Consequently, noise source identification should be misled. This study investigates the fact that the engine structure located around an alternator reflects alternator noise, and the reflected noise acts as another alternator noise source in a heavy-duty diesel engine. The result shows that the alternator noise can be correctly estimated in engine noise by properly including the noise reflection effect.

An Investigation of the Noise in Ship Engine-Room and Cabins for Hearing Protection (I) (청력보호를 위한 선박 기관실 및 선실소음의 조사(I))

  • Yu, Y.H.
    • Journal of Power System Engineering
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    • v.3 no.3
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    • pp.97-103
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    • 1999
  • As the noise of ship engine room is too loud, the engineer who works in a ship engine-room has the trouble of hearing. In this paper deals the investigation of the noise of ship engine room and cabins with the internationally allowable noise exposure level and noise exposure time. Recently, the problem of engine-room noise is more serious because of shipowner wants to make small number and larger size of cylinder. Therefore, engineers work in a ship engine-room for a long time have the trouble of hearing when they are exposed the high noise level. In this study, two kinds of vessels were used to investigate the noise of engine room, engine-control room, bridge, offices and cabins. As criteria of sound levels, A-weighted sound pressure level and octave band pressure level were used.

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A Study on the Development of a Resonator to Reduce the Ship Engine Room Noise (선박기관실의 소음 저감을 위한 차폐공명기의 개발에 관한 연구)

  • Yu, Y.H.
    • Journal of Power System Engineering
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    • v.11 no.4
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    • pp.72-77
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    • 2007
  • It is known that elimination of ship engine room noise is impossible thing, so the working environment in the engine room is getting worse because ships are recently built with huge engines to take higher sailing power. In the yacht and cruise yacht, the engine room noise is more serious because they have bigger engines relative to their hull sizes. The noise generated from the main engine makes the employee to hearing loss and the transmitted noise make the uncomfortable conditions in the cabins of ship. The noise generated by ship engine must be attenuate for the employee and passenger. In yacht and cruise yacht, the noise levels in cabines are the most important criterions to the value of commodities. In this study, the noise absorbtion barrier which have resonators is experimentally studied by the 1/3 octave band noise elimination rates(%).

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Experimental Noise Separation of a Diesel Engine (디젤 엔진소음 (1) ; 실험적 소음 분리기법)

  • 강종민;안기환;박해성;조우흠
    • Journal of KSNVE
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    • v.7 no.5
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    • pp.757-764
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    • 1997
  • The well-developed noise separatrion techniques are applied to the V8 RG8 Diesel engine for the engine noise reduction of a commercial vehicle. For various loads and engine RPM's, the contribution of the combustion oriented noise and the mechanically induced noise was calculated under the small variations of the injection timing. For the given Diesel engine the mechanical noise is dominant for low rpm, and the contribution of the combustion noise becomes greater as the rpm increases. The combustion noise is dominant around 2kHz range or under 50% loading condition.

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The Characteristics of Engine Noise and its Reduction Techniques (엔진 소음, 진동 특성 및 개선방안)

  • 이재갑;여승동
    • Journal of KSNVE
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    • v.7 no.4
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    • pp.689-700
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    • 1997
  • There are many difficulties in designing the engine structure properly due to the strong conflicts between NVH characteristics and the high performance, light weight and low product cost. Many feasible noise reduction techniques should be carefully incorporated to meet such stringent noise requirements. It is also required that the engine development be carried out by introducing concurrent engineering, in which the analysis and test database are usefully applied to the detail designs from the 1st stage. This paper reviews the significance of the noise characteristics of the structure elements in relation to the combustion pressure. The mechanisms of the crank shaft rumbling, which is the main source having the bad influence on the sound quality, are also explained. The influences of dynamic behavior of engine structure on its noise are investigated, followed by discussions on experimental results of the features necessary for the design of low noise engine concepts.

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Using Acoustic Liner for Fan Noise Reduction in Modern Turbofan Engines

  • Azimi, Mohammadreza;Ommi, Fathollah;Alashti, Naghmeh Jamshidi
    • International Journal of Aeronautical and Space Sciences
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    • v.15 no.1
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    • pp.97-101
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    • 2014
  • With the increase in global air travel, aircraft noise has become a major public issue. In modern aircraft engines, only a small proportion of the air that passes through the whole engine actually goes through the core of the engine, the rest passes around it down the bypass duct. A successful method of reducing noise further, even in ultra-high bypass ratio engines, is to absorb the sound created within the engine. Acoustically absorbent material or acoustic liners have desirable acoustic attenuation properties and thus are commonly used to reduce noise in jet engines. The liners typically are placed upstream and downstream of the rotors (fans) to absorb sound before it propagates out of the inlet and exhaust ducts. Noise attenuation can be dramatically improved by increasing the area over which a noise reducing material is applied and by placing the material closer to the noise source. In this paper we will briefly discuss acoustic liner applications in modern turbofan engines.

The Analysis of NVH Characteristics of 4-Cylinerder Diesel Engine Block by Adapting Balancing Shaft (밸런스 샤프트 적용에 따른 4기통 디젤 엔진 블록의 방사소음 특성 개선 해석)

  • Choi, Cheon;Suh, Myung-Won;Kim, Young-Gin
    • Transactions of the Korean Society of Automotive Engineers
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    • v.8 no.5
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    • pp.129-137
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    • 2000
  • The powertrain is an important factor for the interior and exterior noise behavior of the vehicle Thus, the noise vibration and harshness(NVH) behavior of an engine is becoming a major target of the powertrain development. This paper describes the analyses with the aim to reduce the vibration and noise of an advanced inline 4-cylinder diesel engine block by use of CAE methods. The characteristics of an engine block as a main excitation source of car interior noise is studied. Particularly, The effect of balance shaft to reduce the 2nd order engine excitation force is calculated by forced vibration and radiated noise analysis. The engine exitation forces are obtained under real operating conditions. It is shown that the reduction of vibration and noise level by adapting blancing shaft is well predicted and rediated noise is directly related to the surface velocity of engine block.

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Acoustic Enclosure Design of Diesel Engine (디젤엔진의 음향차폐장치 설계)

  • Choi, Hyun;Kim, Young-Chan;Kim, Doo-Hoon;Jeon, Jae-jin
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.481-487
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    • 1997
  • The development of transportation and construction equipment has required higher engine power and lower operation cost. The sound which the engine emits often degrade the performance of the whole system which adopts that engine. Specially the marine engine requires high restriction on the noise level for the customer's comfort and safety. The noise and vibration of Diesel engine must be carefully considered in the early design step. The double antivibration system is effective to increase the efficiency of antivibration, and the acoustic enclosure for reducing the noise level. 2 DOF model was effective to estimate the antivibration performance, which allows to determine the mass of the engine bed and the specification of the engine mount. The mass distribution of the enclosure system can be considered effectively by using the FEM model. The design contains structurally rigid engine bed by FEM, which is for reducing the influence of the flexible vibration, rubber mount selection as well as the acoustic enclosure design.

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Basic Study on the Performance Improvement of HD Diesel Engine (대형 디젤엔진의 소음 개선에 대한 기초 연구)

  • 김규철;이삼구;주봉철;노병준
    • Transactions of the Korean Society of Automotive Engineers
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    • v.9 no.1
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    • pp.181-188
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    • 2001
  • The evaluation of the noise for the an existing engine was carried out to improve the current noise level. The applied techniques were 1m air-borne noise, combustion noise analysis, torsional analysis at the front pulley and sound pressure intensity. In addition, the evaluation of the possibility to the noise reduction by means of wrapping the parts was performed to propose the detailed information in engine design. In view of the obtained results, the following countermeasures were recommended to reduce the current noise level through the above methods. Furthermore, in order to assess the influence of combustion noise on the overall engine noise, the noise test was also performed by the change of intake air temperature up to 5$0^{\circ}C$ in steps of 1$0^{\circ}C$. Finally, the fixed design specifications to reduce the engine noise will be decided in consideration of the test data for proto type engine.

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Exhaust Noise Control of Marine Diesel Engine Using Hybrid Silencer (조합형 소음기를 이용한 박용 디젤 엔진 배기 소음 제어)

  • Lee, Tae-Kyoung;Joo, Won-Ho;Bae, Jong-Gug
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.19 no.7
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    • pp.679-684
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    • 2009
  • Low frequency exhaust noise of marine diesel engine is one of the most important noise sources in vessels. However, conventional absorptive silencers are ineffective to control exhaust noise because of low absorption in the low frequency range. In the paper, exhaust noise control of marine diesel engine was studied by using the hybrid silencer, which was composed of virtually divided array of concentric hole-cavity resonators and conventional absorptive silencer. A series of tests including field tests were performed to investigate the acoustic performance of the hybrid silencer. Consequently, its high performance of 5${\sim}$10 dB noise reduction in the low frequency range was confirmed and it is expected to be very helpful in reducing the exhaust noise of marine diesel engine.