• Title, Summary, Keyword: Engine Noise

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Effect of Airborne Noise from Ship Machinery on Underwater Noise (선박의 장비 공기소음이 수중소음에 미치는 영향)

  • Kim, Hyun-Sil;Kim, Jae-Seung;Kim, Bong-Ki;Kim, Sang-Ryul;Lee, Seong-Hyun
    • Journal of the Society of Naval Architects of Korea
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    • v.48 no.6
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    • pp.569-574
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    • 2011
  • In research vessels or naval ships, airborne noise from machineries such as diesel engine is the major source of underwater noise at low speed. In this paper, effect of engine noise on underwater noise is studied by considering two paths; sound radiation from hull plate and direct airborne noise transmission through hull plate. SEA (Statistical energy analysis) is used to predict hull plate vibration induced by engine noise, where SEA model consists of only two subsystems; engine room air space and hull plate. The pressure level in water is calculated from sound radiation by plate. Engine noise transmission through hull plate is obtained by assuming plane wave propagation in air-limp plate-water system. Two effects are combined and compared to the measurement, where speaker is used as a source in engine room and sound pressure levels in engine room and water are measured. The hydrophone is located 1 m away from the hull plate. It is found below 1000 Hz, prediction overestimates underwater sound pressure level by 5 to 12 dB.

The Effect of Active Chassis Vibration Control on the Engine Booming Noise (능동 샤시 진동 제어가 실내 엔진 부밍 소음에 미치는 영향)

  • 정병보;박만복;이용욱;박영진;이종원;강구태;채창국
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.991-995
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    • 2002
  • The engine booming noise heard inside a vehicle's cabin is due to the engine vibration that's transferred to the chassis in the form of structural vibration and it often causes discomfort to the passenger. In an effort to seek out the possible relation between the engine booming noise and the engine vibration of a vehicle, a position on the engine mount was selected and the vibration transmission through the position was attenuated to observe the corresponding change in the noise level inside the cabin. A system consisting of an actuator and a hybrid controller that has both the feed-forward and feed-back capabilities was developed in order to carry out the experiment.

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Identification of Airborne-noise Source and Analysis for Noise Source Contribution of a GDI Engine Using Sound Intensity Method (음향 인텐시티법을 이용한 GDI 엔진 소음원 규명 및 소음 기여도 분석에 관한 연구)

  • Kim, Byung-Hyun;Lee, Sang-Kwon;Yoon, Joon-Seok;Shin, Ki-Chul;Lee, Sang-Jik
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.22 no.10
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    • pp.985-993
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    • 2012
  • In this paper, a new method is proposed to estimate the sound pressure generated from gasoline direct injection (GDI) engine. There are many noise sources as much as components in GDI engine. Among these components, fuel pump, fuel injector, fuel rail, pressure pump and intake/exhaust manifolds are major components generated from top of the engine. In order to estimate the contribution of these components to engine noise, the total sound pressure at the front of the engine is estimated by using airborne source quantification (ASQ) method. Airborne source quantification method requires the acoustic source volume velocity of each component. The volume velocity has been calculated by using the inverse method. The inverse method requires many tests and has ill-condition problem. This paper suggested a method to obtain volume velocity directly based on the direct measurement of sound intensity and particle velocity. The method is validated by using two known monopole sources installed at the anechoic chamber. Finally the proposed method is applied to the identification and contribution of noise sources caused by the GDI components of the test engine.

Effects of Exhaust Pipe Curvature on the Exhaust Noise of a Diesel Engine (디이젤 엔진에서 排氣管의 屈曲度가 排氣 騷音에 미치는 影響)

  • 문병수;김옥현;서정윤
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.10 no.3
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    • pp.392-398
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    • 1986
  • It is often occurred that exhaust pipe of an internal combustion engine should be bent due to some geometrical constraints. Especially for automobiles most of exhaust pipes of engines have curvature to avoid rear axles. In this paper effects of pipe curvature on the exhaust noise of a diesel engine have been studied experimentally. Experiments were carried out on a 4-cycle, 2164cc diesel engine. Two types of curvature, circular arc and retangle, were tested. Sound pressure level (SPL) and power spectrum of the exhaust noise were measured by inserting bent pipes of different curvature dimensions into the exhaust pipe at various engine operating conditions. The following results were obtained from this study. Among the engine operating conditions the exhaust noise was affected mainly by engine revolution speed. The noise was reduced by the circular arc bent pipe. The effectiveness of an arc bent pipe on the noise reduction was dominated by its arc angle and the maximum noise reduction was obtained by the angle of 180.deg.. But the noise reduction could not be obtained by the rectangular bent pipe, and at high engine speed the noise was rather increased due to turbulence of exhaust gas.

A Study on Spectrum Analysis of the Underwater Noise by Engine Generating in Small Fishing Boat (소형어선의 기관의 수중소음 스펙트럼 분석에 관한 연구)

  • 최한규
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.35 no.3
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    • pp.323-327
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    • 1999
  • Most of the underwater noise emitted by small fishing boat are owing to vibration of main engine and generator etc.. This paper describe on the spectrum analysis of underwater noise by engine generating in small fishing boat in order to build up comfortable environment for fisheries man and to reduce ambient noise. The obtained results are summerized as follows:1. When the underwater noise of 10ton class fishing boat measure and the frequency spectrum in varied revolution of engine 750, 900, 1000rpm analyze, the frequency pattern is similar to each other, the faster revolution of engine increase, the higher frequency spectrum level becomes. 2. In comparison of spectrum level of underwater noise between 10ton class and 14ton class fishing boat, the former level is higher than the latter. 3. Frequency spectrum pattern of two 14ton class fishing boat is similar to each other but spectrum level is a little difference, it is suggested to different by fitting condition of engine.

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Radiated Noise Analysis of Marine Diesel Engine from Structural Vibration (선박용 디젤 엔진의 구조진동에 의한 방사소음 해석)

  • Kim, Dae-Hwan;Jeong, Weui-Bong;Park, Jeong-Geun;Hong, Chin-Suk
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.18 no.1
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    • pp.26-34
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    • 2008
  • This paper summarizes a design procedure of radiated noise from engine blocks of marine engines. This air-borne noise is one of the significant noise contributors including the aeroacoustic noise due to intake and exhaust and the re-radiation due to structure-borne noise. Excitation forces by engine operations are evaluated taking into account the power generation mechanism from the burning process to the subsequence motion of internal parts; piston, connecting rod, and crank shaft. The acoustic transfer vector method is incorporated to effectively simulate the radiated noise field under the various operation conditions. A contribution analysis for the various excitations to the radiated noise is conducted. It is found that the firing pressure is the main source of the radiated noise, and so the structure of the cylinder can be modified to significantly reduce the radiated noise from the engine block.

Radiated Noise Analysis of Marine Diesel Engine from Structural Vibration (선박용 디젤 엔진의 구조진동에 의한 방사소음 해석)

  • Kim, Dae-Hwan;Hong, Chin-Suk;Jeong, Weui-Bong;Park, Jeong-Geun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.1060-1065
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    • 2007
  • This paper summarizes a design procedure of radiated noise from engine blocks of marine engines. This air-borne noise is one of the significant noise contributors including the aeroacoustic noise due to intake and exhaust and the re-radiation due to structure-borne noise. Excitation forces by engine operations are evaluated taking into account the power generation mechanism from the burning process to the subsequence motion of internal parts; piston, connecting rod, and crank shaft. The acoustic transfer vector method is incorporated to effectively simulate the radiated noise field under the various operation conditions. A contribution analysis for the various excitations to the radiated noise is conducted. It is found that the firing pressure is the main source of the radiated noise, and so the structure of the cylinder can be modified to significantly reduce the radiated noise from the engine block.

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The Study of the improvement of the sound quality using the target profile of combustion pressure (목적 연소압 형상을 이용한 음질 개선에 관한 연구)

  • Hwang, C.K.;Min, B.D.;Kim, I.S.
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.649-653
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    • 2006
  • Engine Noise is composed of the mechanical and combustion noise. The contribution of combustion noise is generally bigger than the contribution of the mechanical noise at idle condition in DI diesel engine. That noise usually makes a roughness problem at the fundamental engine order. It is difficult to remove the modulation frequency so we have to directly reduce the combustion noise. The key effect of combustion noise reducing solution is the modification of the combustion pressure profile. It is accomplished by the multiple injection method and we solved the 400Hz combustion noise and improved the sound quality at idle condition in DI diesel engine.

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Simulation on the Reduction of Interior Noise using the Transfer Path Analysis of the Active Engine Mount (엔진마운트의 전달경로해석을 통한 실내소음저감 시뮬레이션)

  • Lee, Choong-Hwi;Kim, Young-Ho;Choy, Hyun-Joon;Won, Jong-Sik
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.166-170
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    • 2008
  • In this study, it proved that transfer path analysis is a proper technique to estimate the interior noise from comparing measured interior noise in case of 3 point supported engine mount system. And the simulation of the vibration isolation for active engine mount using FXLMS algorithm is performed. Also, it verified that reduction of estimated interior noise from transfer path analysis and simulation of the vibration isolation.

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Prediction of the Radiated Noise from the Vehicle Intake System (자동차 흡기계의 방사소음 예측에 대한 연구)

  • Kim, Hoi-Jeon;Ih, Jeong-Guon;Lee, Seong-Hyun;Shinoda, K.;Kitahara, S.
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.105-108
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    • 2005
  • The radiated noise from the automotive intake system should be predicted at the design stage. To this end, the precise measurement of in-duct acoustic source parameters of the intake system, i.e., the source strength and source impedance, is essential. Most of previous works on the measurement of acoustic source parameters were performed under a fixed engine speed condition. However, the requirement of vehicle manufacturer is the noise radiation pattern as a function of engine speed. In this study, the direct method was employed to measure the source parameters of engine intake system under a fixed engine speed and engine run-up condition. It was noted that the frequency spectra of source impedance hardly changes with varying the engine speed. Thus, it is reasonable to calculate the source strength under the engine run-up condition by assuming that source impedance is invariant with engine speed. Measured and conventional source models, i.e., constant pressure source, constant velocity source, and non-reflective source, were utilized to predict insertion loss and radiated sound pressure level. A reasonable prediction accuracy of radiated sound pressure level spectra from the intake system was given in the test vehicle when using the measured source characteristics which were acquired under the operating condition.

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