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Sound Reduction Control in Acoustic Enclosure with air ventilation

Acta Mechanica Solida Sinica 2023年第6期36卷 763-769页

作者： Mengyi Liu Xiaoming Zhou Key Laboratory of Dynamics and Control of Flight Vehicle of Ministry of Education Beijing Institute of TechnologyBeijing 100081China School of Aerospace Engineering Beijing Institute of TechnologyBeijing100081China

An acoustic enclosure system with both interior sound reduction and air ventilation is designed and *** system consists of a rectangular enclosed space coupled with ventilated metamaterials and microperforated panels(MPPs).By modeling the ventilated metamaterial as an impedance boundary condition,an analytic model is developed to characterize the frequency response of interior acoustic fields and evaluate the sound reduction performance of MPP *** simulations are conducted to validate the accuracy of the theoretical *** is found that the resonance response of the enclosure system can be suppressed by proper arrangement of the *** with open area for airflow,the system still possesses good sound isolation originating from the low-transmission behavior of the ventilated *** proposed model system may find potential applications in noise control engineering.

关键词： Acoustic enclosure Sound reduction Microperforated panel air ventilation

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Experimental and Numerical Investigation of the Diffusion of a Confined Wall Jet through a Perforated Plate

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Open Journal of Fluid Dynamics 2022年第2期12卷 168-212页

作者： Moussa Diop Denis Flick Graciela Alvarez Jean Moureh Refrigerating Process Engineering Unit INRAE Antony Antony France Université Paris Saclay INRAE AgroParisTech UMR SayFood Massy France

When performing numerical modeling of fluid flows where a clear medium is adjacent to a porous medium, a degree of difficulty related to the condition at the interface between the two media, where slip velocity exists, is encountered. A similar situation can be found when a jet flow interacts with a perforated plate. The numerical modeling of a perforated plate by meshing in detail each hole is most often impossible in a practical case (many holes with different shapes). Therefore, perforated plates are often modeled as porous zones with a simplified hypothesis based on pressure losses related to the normal flow through the plate. Nevertheless, previous investigations of flow over permeable walls highlight the impossibility of deducing a universal analytical law governing the slip velocity coefficient since the latter depends on many parameters such as the Reynolds number, porosity, interface structure, design of perforations, and flow direction. This makes the modeling of such a configuration difficult. The present study proposes an original numerical interface law for a perforated plate. It is used to model the turbulent jet flow interacting with a perforated plate considered as a fictitious porous medium without a detailed description of the perforations. It considers the normal and tangential effects of the flow over the plate. Validation of the model is realized through comparison with experimental data.

关键词： Perforated Plate Porous Medium Wall Jet air ventilation Aeraulic Turbulence Diffusion

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Experimental Study of the Diffusion of a Confined Wall Jet through a Perforated Plate: Influence of the Porosity and the Geometry

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Open Journal of Fluid Dynamics 2022年第1期12卷 96-126页

作者： Moussa Diop Denis Flick Graciela Alvarez Jean Moureh Refrigerating Process Engineering Unit INRAE Antony Antony France UMR SayFood AgroParisTech INRAE Université Paris Saclay Massy France

This paper investigated lateral diffusion of a confined two-dimensional wall jet (air inlet height: 5 cm) through a perforated plate. We considered two plates with porosities of and . The plates were positioned at distances of 10 cm and 20 cm below the jet inlet. The experiments were realized using 2D Laser Doppler Anemometer (LDA). Different profiles of mean and fluctuating velocities are presented. The presence of a perforated plate strongly modified the airflow pattern compared to an empty enclosure. The velocities above and below the plate depend on several parameters, including the porosity and the plate’s position relative to the inlet slot and the longitudinal position. The difference between the flow velocity above and below the plates could not be related using a universal formula that depends on these parameters. We also investigated the influence of a porous media of a height of 20 cm (a stack of spheres having a diameter of 3.75 cm) located below the perforated plate. The results highlight that the porous medium strengthens the effects of the perforated plate on the flow.

关键词： Porous Medium Perforated Plate Wall Jet air ventilation Aeraulic Turbulence Diffusion

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Environmental Benefit to Enhance the Dust Filtration in a Subway ventilation Chamber

Environmental Benefit to Enhance the Dust Filtration in a Su...

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第七届亚洲气溶胶会议

作者： Hyun Hee Lim Ju Yeol Lee Young Min Jo Department.of Environmental Engineering Kyung Hee University South Korea 446-701

air quality of underground railway is of critical interests in Seoul, Korea. National government has emphasized the stringent management of IAQ of metro-subway. In order to satisfy the legislative standard and public needs, air purification must be much more enhanced with the addition of high quality control facilities. Thus, this work focused on the review of cost effectiveness for replacing fine dust filters. The inflow amount of PM10 and PM2.5 into the test ventilation chamber in which deals with the air, 900 CMM, was 19.4 kg/yr and 8.9 kg/yr respectively. It corresponds to US $ 5,857 for PM 10 and US $ 6,608 for PM2.5 based on the environmental cost evaluation. The current filtration system collects approximately 55% of the inlet PM10 and 35% of PM2.5. Even if it obeys the National IAQ regulation for platforms and ticket rooms, civic groups strongly insist better quality of air inside. Thus, additional facilities to improve the air filtration up to 80% of PM10 and 55% of PM2.5 would cost US$ 8,756 per year. However, the increase of environmental benefit on the atmospheric dust will in part compensate the cost.

关键词： air ventilation Subway IAQ Filtration Electret filter Environmental benefit

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