• Title, Summary, Keyword: Engine Noise

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The Underwater Propagation of the Noise of Ship's Engine (기관소음의 수중전파에 관한 연구)

  • 박중희
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.16 no.2
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    • pp.69-76
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    • 1980
  • This paper describes the measurement of the underwater noises produced by the engine vibration around the engine room of stern trawler MIS Sae-Ba-Da(2275GT, 3,600 PS) and pole kner M/S Kwan-Ak-San (243 GT, 1000 PS) while the ship is stopping. The underwater noise pressure level was measured with the underwater level meter of which measuring range is 100 to 200 dB(re bLPa). A and B denotes the maximum pressure level measured at right beneath the bottom of the engine room, while the main engine of the Sae-Ba-Da revoluted at 750 and 500 rpm, respectively. C denotes that of the main engine of the Kwan-Ak-San revoluted at 350 rpm, and D that of the generator of the Sae-Ba-Da revoluted at 720 rpm. Thus A, B, C and D were set for the standard sound source for the experiment. The results obtained are as follows: 1. The noise Pressure level at A, B, C and D were 170.5,165,153 and 158dB, respectively. 2. When the check points distanted vertically 1, 10, 20, 30, 40, 50m from the sound source, the underwater noise presure levels were 170.5, 155, 148, 144 and 138 dB and the directional angle was 116\ulcorner in case of A. 3. The sound level attenuated at the rate of 20dB per 10" meters of the horizontal distance from the sound sources. 4. The frequency distribution of the noise was 100Hz to 10KHz and predominant frequency was 700 to 800Hzminant frequency was 700 to 800Hz

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Acoustic holography for an engine radiation noise using equivalent sources (등가음원을 이용한 엔진 방사 소음의 음향 홀로그래피에 대한 연구)

  • Jeon, In-Youl;Ih, Jeong-Guon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.1101-1106
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    • 2004
  • This study presents the reconstruction of sound field radiated from an automotive engine using equivalent sources. Basic concept of the method presented is to replace the engine noise source with elementary sources of multipoles, e.g., monopoles and dipoles. The so-called Helmholtz equation least-squares (HELS) method can reconstruct the sound radiation fields from spherical geometries in a series expansion of spherical Hankel functions and spherical harmonics. In this paper, multi-Point, multipole equivalent sources are employed to reconstruct the sound field radiated from an automotive engine with a fixed rotation speed. To ensure and improve the accuracy of reconstruction, the spatial filters of multipole coefficients and wave-vectors are adopted for suppressing the adverse effect of high-order multipoles. Optimal filter shapes are designed with regularization parameters minimizing the generalized cross validation (GCV) function between actual and reproduced model. After regeneration of field pressures using the proposed method as many as necessary, the vibro-acoustic field of an engine could be reconstructed by using the BEM-based near-field acoustic holography (NAH) technique in a cost-effective manner.

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Experimental Study of Engine Mount Optimization to Improve NVH Quality (NVH 성능향상을 위한 엔진마운트 최적설계에 관한 실험적 연구)

  • 이준용
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.330-337
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    • 1996
  • The purpose of engine mount system is to reduce the noise and vibration caused by engine vibration, and to decouple the roll and bounce mode at idle. To reduce the noise and vibration level in a vehicle, it is important to make the design optimization of engine mount system that considered the moment of inertia and inclination of mount rubber. As a result, according to the definition of Torque Rool Axis (TRA), the vibration axis at idle must be on the TRA or very close to it. In this paper, we studied the effect of the design optimization of engine mount system. And we have a good NVH performance.

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A Study of the excitation force of an engine system for construction equipment (건설기계 엔진 시스템의 가진력 예측 모델 개발)

  • Kim, Woohyung;Kim, Seongjae;Kim, Indong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.654-657
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    • 2014
  • In this paper, we study the analytical method to predict the excitation forces for the engine system. The engine system on the construction equipment is one of the important power sources, and the characteristics of the engine decide the performance of noise and vibration for the equipment. We predict the excitation forces using the geometrical data of the crank system and the combustion pressure in the cylinder. The excited forces are represented by the torque fluctuation above the center of the crank shaft.

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The source identification of noise & vibration using characteristics of vibro-acoustic transmission (진동-음향 전달특성을 이용한 진동 및 소음원의 규명)

  • Oh, Jae-Eung;Kim, Dong-Sup;Kim, Woo-Taek;Kang, Hyun-Seok
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.495-499
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    • 2000
  • The booming noise of a vehicle is usually caused by the vibration of the vehicle's body transmitted from the engine through the mounting system. Thus the engine mounting system must be cautiously designed to reduce the noise. Vector synthesis analysis is performed to predict the booming noise when the characteristic of the engine mounting system is changed., i.e., when magnitudes and phases of vibratory forces after the mounts are altered. To effectively use the method, the concept of 'effectiveness' is introduced to identify the contributions of each vibration sources and transmission paths to interior noise. When the magnitudes and phases of the forces due to the engine vibration are changed, the synthesized interior booming noise level is predicted by the vector synthesis diagram. Thus, the optimum characteristics of the forces are obtained through the simulations of the vector synthesis analysis. It is shown that the vector synthesis method can be used to obtain the optimum design characteristic of the mounting system to control the interior booming noise of a vehicle.

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Noise Optimization of the Cooling Fan in an Engine Room by using Neural Network (신경망이론을 적용한 엔진룸내의 냉각팬 소음 최적화 연구)

  • Chung, Ki-Hoon;Choi, Han-Lim;Kim, Bum-Sub;Kim, Jae-Seung;Lee, Duck-Joo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.116-121
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    • 2002
  • Axial fans are widely used in heavy machines due to their ability to produce high flow rate for cooling of engines. At the same time, the noise generated by these fans causes one of the most serious problems. This work is concerned with the low noise technique of discrete frequency noise. To calculate the unsteady resultant force over the fan blade in an unsymmetric engine room. Time-Marching Free-Wake Method is used. From the calculations of unsteady force on fan blades, noise signal of an engine cooling fan is calculated by using an acoustic similarity law. Noise optimization is obtained from Neural Network which is constructed based on the calculated flow rate and noise spectrum.

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Noise Optimization of the Cooling Fan in an Engine Room by using Neural Network (신경망이론을 적용한 엔진룸내의 냉각팬 소음 최적화 연구)

  • Chung, Ki-Hoon;Park, Han-Lim;Kim, Bum-Sub;Kim, Jae-Seung;Lee, Duck-Joo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.318.2-318
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    • 2002
  • Axial fans are widely used in heavy machines due to their ability to produce high flow rate fur cooling of engines. At the same time, the noise generated by these fans causes one of the most serious problems. This work is concerned with the low noise technique of discrete frequency noise. To calculate the unsteady resultant force over the fan blade in an unsymmetric engine room, Time-Marching Free-Wake Method is used. From the calculations of unsteady force on fan blades, noise signal of an engine cooling fan is calculated by using an acoustic similarity law. (omitted)

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Transfer Path Analysis on the Passenger Car Interior Noise (승용차 실내소음의 전달경로 해석)

  • 지태한;최윤봉
    • Journal of KSNVE
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    • v.9 no.1
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    • pp.97-102
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    • 1999
  • Structure-borne noise is an important aspect to consider during the design and development of a vehicle. In this work. it was desired to identify the primary paths associated with structure-borne noise generated from the engine and front suspension. An experimental source-path-receiver model was used to characterize the system. A variety of primary sources such as engine. tires or exhaust system generate vibrations of the inner surfaces of the passenger compartment of a vehicle which subsequently radiate noise. The source was characterized by the force acting at the engine-to-body interface. and the path was characterized by pressure over force FRF's. The excitation forces were indirectly determined using dynamic stiffness of rubber mount or the system accelerance matrix. Through these analysis, path contribution diagram which is well expressed primary noise path is obtained.

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A Study of Eliminating the Vehicle Noise of Engine RPM from the Friction Noise between Tire and Road Pavement by Using a NCPX Method (NCPX 계측방법을 이용한 타이어/노면 사이에서 발생하는 마찰소음에 대한 차량자체에서 발생하는 소음 제거 연구)

  • Han, Bong-Koo;Kim, Do Wan;Mun, Sungho;Kim, Ha-Yeon
    • International Journal of Highway Engineering
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    • v.15 no.4
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    • pp.31-42
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    • 2013
  • PURPOSES : The purpose of this study is to eliminate the noise of the vehicle after measuring the friction noise obtained from the NCPX (Noble Close ProXimity) method. The pure friction noise between the tire and road pavement could be determined from filtering the compositeness of sound and the influence of the vehicle noise. METHODS: The noise magnitude could be determined by analyzing the sound pressure level (SPL) and sound power level (PWL) along with the noise frequency of a FFT (Fast Fourier Transform) analysis as well as CPB (Constant Percentage Bandwidth) analysis. RESULTS: When the test for measuring the friction noise originated somewhere between tire and road pavement is performed with NCPX method, it must be fulfilled by attaching the surface microphone near the tire. In this condition, the surface microphone can measure the friction noise occurred at between tire and pavement, the chassis noise from the engine and power transfer units, the fluctuating aerodynamic noise, and the turbulence noise directly affected to the surface microphone. By using the NCPX method, the noise occurred at the vehicle must be eliminated for measuring the friction noise between tire and pavement from the traffic noise. CONCLUSIONS: The vehicle's testing engine noise depends on the vehicle and road types. The effect of vehicle's engine noise is less than the friction noise occurred at between tire and pavement at less than 1% effect.

The effects of engine's misfiring condition on the dynamic behaviour of resilient mounting systems (엔진의 착화실패가 탄성지지계의 동적거동에 미치는 영향)

  • 손석훈;장민오;김성춘;김의간
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.188-193
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    • 1996
  • The purpose of resilient mounting for marine engine is to prevent noise and ship damages caused by engine vibration. Although many researches for the resilient mounting system have been carried out, these results have limit to apply on the marine engine systems. Because marine engine generally have low speed operating range and have to consider misfiring condition. In this paper, we studied the effect of engine's misfiring on the resilient mounting systems. And the influences of design parameters, such as dynamic characteristics and location angles of resilient rubber mountings, were also examined on the single and double resilient mounting systems.

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