• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1991년도 춘계학술대회논문집; 한국해사기술연구소, 대전; 1 Jun. 1991
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• pp.11-15
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• 1991

본 연구는 높은 유속에서 다공형 소음기의 성능 시험을 통하여 유속의 영향 을 검토하고 이피던스 모델에 관하여 평가하기 위한 것이다. 유속이 높은 경 우에는 유동에 의한 자체 소음(self noise)이 크기 때문에 실험에 많은 어려 움이 따르게 되므로 지금까지 최대 통과유속의 마하수가 0.2를 넘지 못하였 다. 그러나 본 연구에서는 실험 장치에 세밀한 주의를 기울여 마하수 0.3까 지 실험하였으며, 실험결과를 이미 발표된 임피던스 모델[6]을 이용한 이론 예측과 비교 검토하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제16권5호
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• pp.77-84
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• 1992

In the most of acoustic system with low flow rate and low pressure level, one-dimensional, linear modeling techniques are used very well. At low frequency, the tube is modeled as inertia element and cavity as capacitance element, and to extend the range of frequency normal mode oscillators are represented. Bond graph modelling techniques are proposed to predict TL (Transmission Loss) and time response which is impossible by transfer matrix in muffler system. A simple acoustic filter which consists of several tubes and cawities is analyzed in both time and frequency domain.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1993년도 춘계학술대회논문집; 한국과학연구소, 21 May 1993
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• pp.115-122
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• 1993

본 연구의 목적은 다공관 소음기의 설계변수인 공동과 다공관의 치수 및 구 멍배열의 변화에 따른 휘파람소리의 발생특성을 실험에 의하여 체계적으로 구하는데 있다. 소음기의 각 설계변수마다 유속변화에 따른 휘파람소리가 발 생하는가를 확인하고 발생하게 되면 스펙트럼 분석을 통하여 휘파람 소리의 주파수특성을 구한다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 춘계학술대회 논문요약집
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• pp.268-268
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• 2004

머플러는 소음의 저감과 공기 정화의 특성으로 인해 자동차와 중장비에 적용되고 있다 최근에는 강화되고 있는 엄격한 환경규제를 만족하기 위해 그 설계와 제조에 있어 그 중요성이 높아지고 있으며, 머플러 튜브의 형태와 타공의 개수 및 배열은 다양한 형태로 연구가 이루어지고 있다. 이 중에서 튜브의 타공은 차량의 중량과 기능에 따라 다양한 형태를 가지며, 모델수의 증가와 출시기간의 단축으로 인해 튜브의 타공기술은 머플러 시장의 경쟁력을 좌우할 정도로 중요해 지고 있다.(중략)

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.1062-1066
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• 2004

In this study, refrigerant noise at connection of capillary tube and evaporator is investigated. Mechanism of refrigerant noise generation is examined in side-by-side type home refrigerator with two evaporators. It is found that the refrigerant noise is generated during refrigeration room fan-off (R-fan of) for that type refrigerator. The reason is that mass flow rate gets down during R-fan of and flow pattern is changed at outlet of capillary tube. We suggest designs for reduction of refrigerant noise with horizontal double expansion device, muffler, and accumulator. To evaluate those improved designs, sound quality index is used.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.346-352
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• 2002

This paper is the experimental study to estimate the influence of various design parameters on the performance of mufflers with perforated tubes and through-flow partitions. Muffler types considered in the present work include through-flow chamber, through-flow chamber with partition, and cross-flow chamber. The influences of the design parameters on the performance of the mufflers can be outlined as follows. In the case of the through-f]ow type mufflers, increasing the tube thickness and the hole diameter of the perforated tubes does not change the maximum value of the transmission loss but decrease the cutoff frequency. In the case of the through-flow with partitions type mufflers, it is shown that combining a fe w short chambers and long chambers can modify the frequency locations of the resonance frequencies to optimize the performance of the mufflers. For the case of the cross-flow type mufflers, it is shown that the transmission loss of the mufflers is mainly affected by the lower porosity when the porosities are different in both sides of the plug. Overall, it is shown that performance of the through-flow type with partition type mufflers is excellent in the lower frequency region, where the cross-flow type mufflers have better performance in the higher frequency region.

• 한국전산유체공학회지
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• 제9권2호
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• pp.11-17
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• 2004

CFD analysis was performed to figure out flow behavior in the inlet plenum of new research reactor where coolant is injected to the flow tubes with the fuel assembly. The computation results showed that large-scale vortices are generated in the inlet plenum by flow stream injected from inlet pipe. These vortices are divided into small vortices and reversed their revolution. They may lead to flow-induced vibration of fuel assembly, moreover, which has been regarded as a cause of fretting wear of fuel assembly. Also there is an another important thing that average velocity of each flow-tube is uneven showing difference in maximum 18%. So it has been suggested that perforated baffle will be installed to prevent the formation of vortex in the inlet plenum. Two perforated baffles, one is flow skirt and the other is muffler type flow straightener, were proposed and their effect was evaluated using commercial CFD code, Fluent. According to CFD analysis for two perforated baffles, it was confirmed that both of them can prevent or reduce vortex formation in the inlet plenum and make average velocity of each flow tube more even.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.686-689
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• 2006

In a wheel loader, the tail-pipe is installed at the exhaust tube of muffler for the reduction of exhaust noise and the cooling of engine room however, the cabin noise level can be largely increased due to the tail-pipe. In this paper, to grasp and reduce the cabin noise, a series of noise and vibration tests were carried out in addition to numerical simulations. As a result, the transmission path of exhaust noise toward the cabin was exactly identified and the improved shape of tail pipe, that can reduce the cabin noise, was derived through various numerical simulations and real tests.

• 한국소음진동공학회논문집
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• 제16권12호
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• pp.1238-1243
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• 2006

In a wheel loader, the tail-pipe is installed at the exhaust tube of muffler for the reduction of exhaust noise and the cooling of engine room, however, the cabin noise level can be largely increased due to the tail-pipe. In this paper, to grasp and reduce the cabin noise, a series of noise and vibration tests were carried out in addition to numerical simulations. As a result, the transmission path of exhaust noise toward the cabin was exactly identified and the improved shape of tail pipe, that can reduce the cabin noise, was derived through various numerical simulations and real tests.

• International Journal of Naval Architecture and Ocean Engineering
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• 제6권4호
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• pp.935-946
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• 2014

This paper investigates the noise transmission performance of industrial mufflers widely used in ships based on the CAE modeling and simulation. Since the industrial mufflers have very complicated internal structures, the conventional Transfer Matrix Method (TMM) is of limited use. The CAE modeling and simulation is therefore required to incorporate commercial softwares: CATIA for geometry modeling, MSC/PATRAN for FE meshing and LMS/SYSNOISE for analysis. Main sources of difficulties in this study are led by complicated arrangement of reactive elements, perforated walls and absorption materials. The reactive elements and absorbent materials are modeled by applying boundary conditions given by impedance. The perforated walls are modeled by applying the transfer impedance on the duplicated node mesh. The CAE approach presented in this paper is verified by comparing with the theoretical solution of a concentric-tube resonator and is applied for industrial mufflers.