Methods for evaluating in-duct noise attenuation performance in a muffler design problem

Lee, Jong Kyeom; Oh, Kee Seung; Lee, Jin Woo

doi:10.1016/j.jsv.2019.114982

Cited by 34 publications

(12 citation statements)

References 36 publications

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“…In addition, we control the absorption frequency at 230-330 Hz, which covers with the main noise frequencies of household appliances in our daily life. [43][44][45] Therefore, the AAVMA absorber could effectively reduce the noise pollution caused by the high penetration ability of low-frequency sounds. In the future, the demonstrated AAVMA can be developed into stunning applications, such as intelligent window silencers, which not only effectively solves the influence of external noise, but also provides a fresh air and bright working environment.…”

Section: Discussionmentioning

confidence: 99%

Automatically Adaptive Ventilated Metamaterial Absorber for Environment with Varying Noises

Tian

et al. 2021

Adv Materials Technologies

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thickness, health and environment issues, fire resistance, moisture resistance, and durability issues. [1][2][3][4] In the past two decades, varieties of artificial structures, collectively called "acoustic metamaterials," have been designed to manipulate sound waves beyond natural limits. [5][6][7][8][9][10][11][12][13] For example, low-frequency (<500 Hz) sound waves have strong penetration ability, long propagation distance, and low attenuation coefficient, hence it is still a great challenge to deal with low-frequency noises. [1,3,4,14] In the last decade, diverse sound-absorbing metamaterials in subwavelength scales have been designed, which generally increase the density of states at targeted low-frequencies in the metamaterials in order to enhance the dissipation of sound energy. [15][16][17][18][19][20][21][22][23][24][25] However, for most acoustic metamaterials, their targeted frequencies and operating functions can hardly be adjusted after being fabricated. It is hence an intrinsic barrier for their applications in scenarios where the frequencies of noise can change over time.To overcome this stringent barrier, tunable acoustic metamaterial absorbers have been proposed and investigated in recent years. [26,27] Some tunable mechanisms, mainly employing the mechanical deformations, piezoelectric, and/or magnetic effects, have been presented. [28][29][30][31][32][33] However, they generally require rigid backings to impede sound transmissions, which forbid the transmission of fluids, such as air and water. The absorption of a ventilated acoustic metamaterial composed of subwavelength scatters is usually much smaller compared with its reflection. It is a challenge to break the limit and finally achieve a tunable absorber with simultaneously good absorption and ventilation at low frequencies. [33] Besides, their intricate mechanical, electronic, and magnetic structures are inconvenient and may be unstable for daily applications. [34,35] Moreover, previously designed adjustable metamaterial absorbers could not automatically perceive incident sound to realize intelligent adjustment and absorption. [21,[36][37][38][39][40][41][42][43] A simpler, more adjustable, and more automatic scheme is eagerly needed.Here, we demonstrate an automatically adaptive ventilated metamaterial absorber (AAVMA) for low-frequency sound that can achieve high-efficiency (>90%) absorption for onesided incidence with frequency varying in the working range. The ventilated absorber can automatically monitor the environmental noise and intelligently adjust the sound absorption An automatically adaptive metamaterial sound absorber is designed, which can absorb tunable low-frequency (<500 Hz) sounds under ventilated conditions by designing a feedback circuit to actively detect the noise signals and adjust the sliders on the reconfigurable absorbers. The automatically adaptive ventilated absorber provides an intelligent route to adapt for different low frequencies, through adjusting the sound absorption units directly in accordance with the...

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Section: Discussionmentioning

confidence: 99%

Automatically Adaptive Ventilated Metamaterial Absorber for Environment with Varying Noises

Tian

et al. 2021

Adv Materials Technologies

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“…[2][3][4] It is well known that the internal partition layout strongly affects the noise attenuation performance of a muffler. [12][13][14] The electric power generated by the TEG is a result of the Seebeck effect, 42 which develops across two points of an electrically conducting material due to a temperature difference between the two points. Because the heat sink plate of the TEG on the outside of the muffler is cooled by natural or forced convection, the temperature of the heat source plate should increase.…”

Section: Muffler Design Goalmentioning

confidence: 99%

Partition layout inside a muffler integrated with a thermoelectric generator: Multi-physics analysis and optimal design

Lee

2022

Journal of Low Frequency Noise, Vibration and Active Control

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A multi-physics-analysis-based topology optimization (TO) method is proposed to optimally design the internal partition layout of a muffler integrated with a thermoelectric generator (TEG). The basic equations governing the acoustical behavior, heat transfer, and fluid flow in the muffler are introduced, and their interaction is designated for exact numerical analysis in terms of acoustics, heat transfer, and fluid mechanics. To implement density-based TO, one design variable is assigned to each finite element in the design domain, and interpolation functions suitable for each physics phenomenon are employed. In the TO problem formulation, the sum of the squared acoustic pressures at the outlet of the muffler for multi-target frequencies is selected as an objective function to achieve broadband noise attenuation. The temperature of the TEG and the pressure drop are constrained for high energy recovery efficiency and fluid passage, respectively. The optimization problem formulated for the muffler design is solved for various design conditions. Optimal partition layouts are obtained depending on the location and length of the TEG, the upper limit value of the pressure drop, and the number of target frequencies in the same frequency band. The noise attenuation performances of each partition layout are compared, and their expected recovery energies are calculated. One optimal partition layout is discussed in terms of acoustics, heat transfer, and fluid mechanics. The numerical results strongly support the validity of our proposed method for the optimal design of a muffler integrated with a TEG.

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“…The second strategy is noise reduction along the transmission path. The application of mufflers for this purpose is an attractive option, 15,16 as they provide a high level of attenuation. 17 However, mufflers can only reduce the noise of the air inlet and outlet of the aerodynamic equipment or the noise of ventilation pipes, and cannot significantly protect the cabin crew.…”

Section: Introductionmentioning

confidence: 99%

Experimental study of aerodynamic noise performance of improved air distributor for ships

Guo

Feng

Lei

et al. 2021

Advances in Mechanical Engineering

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In ships, aerodynamic noise from the variable-air-volume fan is a common problem. This study experimentally explores the strategy of reshaping the traditional C-shaped channel structure to an L-shape to reduce noise. The noise level and resistance coefficient of the improved air distributor are analysed, and the results show that the noise of the original air distributor is 56.3 dB(A) under the rated working conditions (static pressure of 800 Pa and flow rate of 350 m3/h), which exceeds the International Maritime Organisation’s (IMO) ship noise limit (55 dB(A)). For the improved air distributor, the noise pressure level is 38.5 dB(A), the sound pressure level of high-frequency noise is reduced by 48% and the peak sound pressure level appears at 125 to 250 Hz, a frequency below the threshold of human hearing. Thus, the reshaping of the channel has a significant noise reduction effect. When the static pressure is 400 Pa and the flow rate is 100 to 500 m3/h, the sound pressure level of the improved air distributor is reduced by 29.9% to 32.2% to become less than 55 dB(A). Thus, the sound pressure level at the outlet of the improved air distributor meets the IMO ship noise standard.

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Methods for evaluating in-duct noise attenuation performance in a muffler design problem

Cited by 34 publications

References 36 publications

Automatically Adaptive Ventilated Metamaterial Absorber for Environment with Varying Noises

Automatically Adaptive Ventilated Metamaterial Absorber for Environment with Varying Noises

Partition layout inside a muffler integrated with a thermoelectric generator: Multi-physics analysis and optimal design

Experimental study of aerodynamic noise performance of improved air distributor for ships

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