• Title, Summary, Keyword: Silencer

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Silencer structure for exhaust noise attenuation performance in the high frequency range (500 Hz 이상 고주파수 영역에서 배기소음 저감을 위한 소음기 구조)

  • KIM, Sang-Am
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.54 no.3
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    • pp.255-261
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    • 2018
  • High power trends in the diesel engines due to engine downsizing do not provide noise attenuation that can be satisfied with the performance of the existing silencer on account of high frequency increases in the exhaust noise. This study improves the attenuation performance of the exhaust silencer of the diesel engine and suggests silencer structure that performs best attenuation performance, especially at the high frequency range in the exhaust noise. It proposes dual silencer structure with an average attenuation performance of 6.4 dB and a maximum of 10.7 dB in the high frequency range (over 500 Hz), and analyzes its characteristics compared with the existing silencer. The performance analysis is performed according to 'Measurements on silencers in situation-ISO 11820:1996 Acoustics' and describes the results of comparative analysis with the existing silencer.

Design Methodology of Composite Reactive Silencer Based on Acoustic Analysis (복합형 반사형 소음기의 음향학적 특성과 설계방법)

  • Kim, Yang-Han;Choi, Jae-Ung;Kim, Yeong
    • Journal of KSNVE
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    • v.1 no.1
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    • pp.29-38
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    • 1991
  • The performance of silencer system is controlled by the geometrical parameters such as the relative location of inlet and outlet ports, size of main chamber, and cross sectional geometry of inlet-outlet ports and main chamber of silencer. In addition to these parameters, the presence of mean flow and temperature gradient along the silencer also affects the acoustic characteristics of silencer system. Due to the complexity of silencer, it is not straight forward to design the appropriate silencer system. In this paper, a design methodology based on an oustic analysis of silencer system is proposed ; low frequency and high frequency tuning method.

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An Experimental Investigation on Noise Reduction Performance of the Absorption and the Resonance Type Duct Silencers (흡음형과 공명형 덕트 소음기의 소음저감 성능에 관한 실험적 고찰)

  • Lee, Young-Sup;Chung, Kwang-Seop;Lee, Dong-Hoon
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.22 no.12
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    • pp.897-901
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    • 2010
  • A silencer has been widely used for the purpose of suppressing the noises propagated from duct of air conditioning system. The absorption type silencer is usually applied to reduce the noise with high frequency bandwidth. On the order hand, the resonance type silencer is applied to reduce the noise with low-middle frequency bandwidth. The insertion loss of silencer is measured in the reverberation room. The cut-off frequency of reverberation room is 100 Hz. The insertion loss of absorption type silencer is more larger than that for resonance type silencer regardless of changing the flow velocity.

A Study on the Design and Testing of 155mm Howitzer Silencer (155mm 화포의 소음기 설계 및 시험평가에 관한 연구)

  • Yeo, Chul-Mo;Park, Sung-Ho;Lee, Hae-Suk;Kim, Young-Seop;Chung, Han-Shik;Jeong, Hyo-Min
    • Journal of Power System Engineering
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    • v.18 no.5
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    • pp.144-149
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    • 2014
  • The silencer of 155mm caliber howitzer is developed to reduce its firing loud noise. This kind of research of a large gun was seldom because its big firing noise does not make significant effect even if to use silencer. Nowadays, military facilities became closely located civilian residential area. The noise would be regarded environmental pollution. So the noise reducing research becomes reconsidered. The previous silencer researches were only dealt with small guns as pistols and rifles moreover their theories was not properly analyzed for a large caliber silencer. The reason was previous researches of a large caliber silencer as 155mm howitzer were limited because their data based on simulation results without actual test by using computational fluid dynamics. In this study, the entire processes of silencer of 155mm caliber howitzer which were design, manufacturing, actual firing test, and analysis of its theories, were performed and showed. In particular, the actual noise of with silencer and without was measured and the results were compared to analyze the effect of silencer.

Study of the Weak Shock Wave Propagating through an Exhaust Pipe Silencer System (배기 소음기내를 전파하는 비정상 충격파의 수치해석)

  • Kweon, Y.H.;Kim, H.D.
    • Proceedings of the KSME Conference
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    • pp.462-467
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    • 2001
  • The present study addresses a computational work of the weak shock wave propagatings inside a silencer system of automobile exhaust pipe. Four different types of the silencer systems and the initial shock wave Mach number $M_s$ of $1.01\sim1.30$ are applied to investigate their effects on the noise reduction and the flow field in a silencer system. The results obtained from the present computational work are compared with the experimental results. The second order total variation diminishing (TVD) scheme is employed to solve the two dimensional, compressible, unsteady, Euler equations. The present computational results predict the experimental results with a quite good accuracy. Of the four silencer systems applied, the most desirable silencer system to reduce the peak pressure at the exit of the exhaust pipe is discussed.

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A Study on the Performance Improvement of Medium Speed Diesel Engine Exhaust Silencer in the Low-frequency Range Using Array Resonators (공명기 배열을 이용한 중속 디젤엔진 배기 소음기의 저주파수 대역 성능 개선 연구)

  • Kim, Young-Hyun;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.693-698
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    • 2009
  • Various acoustic tests were carried out to investigate the acoustic performance of diesel engine exhaust silencers. In order to consider flow effects, the test facility was set up composed of fan, duct and silencer. Using the test facility, insertion loss tests were carried out to improve the acoustic performance in the low-frequency ranges. Through a series of tests, it was found out that the array resonators having multi-perforated holes inside the exhaust silencer, might be very effective in the low frequency range. Consequently, the hybrid-type silencer which is the combination of reflective silencer with array resonators and conventional absorptive silencer, was proposed and its high performance in the low-frequency range was also verified.

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.

Exhaust Noise Reduction of Dry vacuum Pump (건식진공펌프의 배기 소음 저감)

  • Ahn, Young-Chan;Lee, Hae-Jin;Lee, Jung-Yoon;Yang, Jung-Jik;Oh, Jae-Eung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.349-354
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    • 2007
  • This paper considers acoustic analysis of silencer within a Dry vacuum pump. Main object is noise reduction of Dry Vacuum Pump using the silencer. First, we measured SPL and Intensity for noise source identification and then, designed for the silencer corresponding with noise character. 4-pole parameter are used for predicting transmission loss which is one of characteristics of silencer when we designed for silencer. Calculated Transmission Loss to change main effective factor and selected to optimal value using Design of Experiment. Finally, noise reduction is estimated to compare existing silencer with optimal silencer.

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NUMERICAL ANALYSIS FOR A SILENCER OF TANK GUN (대구경 화포의 소음기에 대한 수치해석)

  • Ko S. H.;Lee D. S.;Woo S. D.;Kang K. J.
    • Journal of computational fluids engineering
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    • v.10 no.4
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    • pp.59-65
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    • 2005
  • A numerical analysis was made to investigate the simple silencer for high pressure blast flow fields. Reynolds-Averaged Navier-Stokes equations were solved for an axisymmetric computational domain constructed by multi block grids. A blast flow field without the silencer was also calculated to validate the present numerical method. The effect of pressure diminution for the silencer was calculated by comparing with and without silencer at the atmosphere region. It was found that the tested silencer could achieve 89.4 percent pressure diminution.

A Study on the Absorptive Silencer for Reducing Noise Propagate in Seawater Pipes on Ship (함정의 해수 배관소음 저감을 위한 흡음형 소음기 연구)

  • Seo, Youngsoo;Park, Kyenghoon;Jeon, Jaejin
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.23 no.8
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    • pp.770-776
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    • 2013
  • Fluid-borne noise produced by seawater circulating pumps propagates through the seawater connected pipes and radiates from the hull opening of a ship. This noise causes the increases of underwater radiated noise and self noise of ship. To reduce the noise propagation through the seawater connected pipes, absorptive silencer must be needed. In this paper, theoretical model to analyze the transmission loss of absorptive silencer was presented and the design parameters of absorptive silencer were verified. Theoretical calculations were performed according to a thickness, a length, an internal pressure and mechanical properties of its absorptive material in order to analyze the characteristics of absorptive silencer. From the theoretical calculation results, the absorptive silencer was manufactured and transmission loss was measured in the test facilities. The results of theory and measurement are compared and discussed.