跳至主要内容

Acoustic Absorption Characteristics of Perforated Thin Plate with Air Jets and Cavity

Read  full  paper  at:
http://www.scirp.org/journal/PaperInformation.aspx?PaperID=53991#.VN24eSzQrzE

ABSTRACT
The present paper focuses on the effect of air jets through a perforated thin plate on the characteristics of an acoustic absorption coefficient. We measured the flow rate, internal pressure, acoustic pressure, and transfer function by using an improved acoustic impedance tube. The normal incidence absorption coefficient was calculated from the measured transfer function using transfer function methods. As a result, the frequency characteristics of the acoustic absorption coefficient against the frequency showed a maximum value at the local frequency. The peak frequency of the acoustic absorption coefficient depended on the thickness of the background air space and the thickness of the perforated plate. As the flow rate increased through the micropores, the peak level of the acoustic absorption coefficient also increased until a flow rate of 80 l /min. As the flow rate further increased, the peak level of the acoustic absorption coefficient decreased and that of the high frequency band increased.
 
Cite this paper
Hamakawa, H. , Matsuoka, H. , Yamai, T. , Asakura, K. , Otsuru, T. , Tomiku, R. , Kurihara, E. , Hayashi, H. and Nishida, E. (2015) Acoustic Absorption Characteristics of Perforated Thin Plate with Air Jets and Cavity. Open Journal of Fluid Dynamics, 5, 1-9. doi: 10.4236/ojfd.2015.51001.
 
References
[1]Howe, M.S. (1979) On the Theory of Unsteady High Reynolds Number Flow through a Circular Aperture. Proceedings of the Royal Society London, Series A, 366, 205-223.
http://dx.doi.org/10.1098/rspa.1979.0048
 
[2]Hughes, I.J. and Dowling, A.P. (1990) The Absorption of Sound by Perforated Linings. Journal of Fluid Mechanics, 218, 299-335.
http://dx.doi.org/10.1017/S002211209000101X
 
[3]Dowling, A.P. and Hughes, I.J. (1992) Sound Absorption by a Screen with a Regular Array of Slits. Journal of Sound Vibration, 156, 387-405.
http://dx.doi.org/10.1016/0022-460X(92)90735-G
 
[4]Jing, X. and Sun, X. (1999) Experimental Investigation of Perforated Liners with Bias Flow. The Journal of the Acoustical Society of America, 106, 2436-2441.
http://dx.doi.org/10.1121/1.428128
 
[5]Jing, X. and Sun, X. (2000) Effect of Plate Thickness on Impedance of Perforated Plates with Bias Flow. AIAA Journal, 38, 1573-1578.
http://dx.doi.org/10.2514/2.1139
 
[6]Dupere, I.D.J. and Dowling, A.P. (2002) The Absorption of Sound by Helmholtz Resonators with and without Flow. American Institute of Aeronautics and Astronautics, 2002-2590.
http://arc.aiaa.org/doi/abs/10.2514/6.2002-2590
 
[7]Luong, T., Howe, M.S. and McGowan, R.S. (2005) On the Rayleigh Conductivity of a Bias-flow Aperture. Journal of Fluids and Structure, 21, 769-778.
http://dx.doi.org/10.1016/j.jfluidstructs.2005.09.010
 
[8]Wada, K., Ishii, T. and Morimoto, J. (2012) Acoustic Absorption Characteristics of Sound Waves Interacting with Fine-Scale Jets. 2012 Symposium on Environmental Engineering, No. 12-6, No. 122.
 
[9]Scarpato, A., Tran, N., Ducruix, S. and Schuller, T. (2012) Modeling the Damping Properties of Perforated Screens Traversed by a Bias Flow and Backed by a Cavity at Low Strouhal Number. Journal of Sound and Vibration, 331, 276-290.
http://dx.doi.org/10.1016/j.jsv.2011.09.005
 
[10]Wada, K. and Ishii, T. (2013) Acoustic Absorption of Perforated Plates with Fine Jets: Experimental Results and Analytical Models. Proceedings of 4th International Conference on Jets, Wakes and Separated Flows, Nagoya, 17-21 September 2013, Paper No. ICJWSF2013-1127.
 
[11]Scarpato, A., Ducruix, S. and Schuller, T. (2013) Optimal and Off-Design Operations of Acoustic Dampers Using Perforated Plates Backed by a Cavity. Journal of Sound and Vibration, 332, 4856-4875.
http://dx.doi.org/10.1016/j.jsv.2013.03.030
 
[12]White, F.M. (1994) Fluid Mechanics. Third Edition, McGraw Hill, Boston.
 
[13]Vigran, T.E. (2008) Building Acoustics. CRC Press, Boca Raton.                            eww150213lx
标签：

评论

发表评论

此博客中的热门博文

A Comparison of Methods Used to Determine the Oleic/Linoleic Acid Ratio in Cultivated Peanut (Arachis hypogaea L.)

Cultivated peanut ( Arachis hypogaea L.) is an important oil and food crop. It is also a cheap source of protein, a good source of essential vitamins and minerals, and a component of many food products. The fatty acid composition of peanuts has become increasingly important with the realization that oleic acid content significantly affects the development of rancidity. And oil content of peanuts significantly affects flavor and shelf-life. Early generation screening of breeding lines for high oleic acid content greatly increases the efficiency of developing new peanut varieties. The objective of this study was to compare the accuracy of methods used to classify individual peanut seed as high oleic or not high oleic. Three hundred and seventy-four (374) seeds, spanning twenty-three (23) genotypes varying in oil composition (i.e. high oleic (H) or normal/not high oleic (NH) inclusive of all four peanut market-types (runner, Spanish, Valencia and Virginia), were individually tested ...
发表评论
阅读全文

Location Optimization of a Coal Power Plant to Balance Costs against Plant’s Emission Exposure

Fuel and its delivery cost comprise the biggest expense in coal power plant operations. Delivery of electricity from generation to consumers requires investment in power lines and transmission grids. Placing a coal power plant or multiple power plants near dense population centers can lower transmission costs. If a coalmine is nearby, transportation costs can also be reduced. However, emissions from coal plants play a key role in worsening health crises in many countries. And coal upon combustion produces CO 2 , SO 2 , NO x , CO, Metallic and Particle Matter (PM10 & PM2.5). The presence of these chemical compounds in the atmosphere in close vicinity to humans, livestock, and agriculture carries detrimental health consequences. The goal of the research was to develop a methodology to minimize the public’s exposure to harmful emissions from coal power plants while maintaining minimal operational costs related to electric distribution losses and coal logistics. The objective was...
发表评论
阅读全文

Evaluation of the Safety and Efficacy of Continuous Use of a Home-Use High-Frequency Facial Treatment Appliance

At present, many home-use beauty devices are available in the market. In particular, many products developed for facial treatment use light, e.g., a flash lamp or a light-emitting diode (LED). In this study, the safety of 4 weeks’ continuous use of NEWA TM , a high-frequency facial treatment appliance, every alternate day at home was verified, and its efficacy was evaluated in Japanese individuals with healthy skin aged 30 years or older who complained of sagging of the facial skin.  Transepidermal water loss (TEWL), melanin levels, erythema levels, sebum secretion levels, skin color changes and wrinkle improvement in the facial skin were measured before the appliance began to be used (study baseline), at 2 and 4 weeks after it had begun to be used, and at 2 weeks after completion of the 4-week treatment period (6 weeks from the study baseline). In addition, data obtained by subjective evaluation by the subjects themselves on a visual analog scale (VAS) were also analyzed. Fur...
发表评论
阅读全文