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1.
提出了在微穿孔板后部引入机械阻抗形成组合结构来解决微穿孔板低频吸声性能差的问题。由机械阻抗板两侧质点速度相同得出机械阻抗单元的传递矩阵,采用传递矩阵法将其与空腔、微穿孔板单元串接,建立组合结构理论计算模型;通过分析品质因子获得带宽与机械阻抗板质量成反比;试验得出组合结构在400 Hz附近有系数为0.8以上的吸声峰值,试验结果与理论计算吻合。在传统微穿孔板共振吸声机制的基础上加入机械共振,能够实现在不增加结构厚度的前提下提高低频吸声性能;降低机械阻抗板质量并且适当控制边界阻尼系数可以实现吸声频带的拓宽。  相似文献   

2.
本文提出将马氏微穿孔板理论与传递导纳法相结合,建立简化的微穿孔板吸声结构的有限元仿真计算方法。基于阻抗管法材料吸声系数测试原理建立了吸声系数仿真实验模型,对微穿孔板结构的吸声系数进行了仿真计算,并与理论计算结果做了对比,说明了该简化方法的合理可行。同时,对金属和非金属材料的微穿孔板计算时温度传导系数的影响做了比较说明。  相似文献   

3.
张斌  李林凌  卢伟健 《应用声学》2010,29(2):134-140
计算微穿孔板吸声系数时,假设孔间的相互作用可以忽略。计算具有不同直径微孔的穿孔板吸声系数并提高其计算精度,孔间的相互作用不能再忽略。在马大猷、Melling(梅尔林)等前人研究的基础上,根据声波辐射和传播原理,分析微孔之间的相互作用,通过修正微孔的实际等效长度,得到计及孔间相互作用微孔板吸声系数模型,并进行理论计算和实验测试。研究结果表明:影响微穿孔板吸声系数除结构参数外,还应考虑孔间的相互作用;计及微孔板各孔间相互作用,能提高共振频率、吸声系数理论值的计算精度,计算值逼近实验测试结果。  相似文献   

4.
水下微穿孔吸声体结构设计与试验研究   总被引:3,自引:0,他引:3  
根据马大猷院士的微穿孔板(MPP)理论,提出在可设计的夹芯复合隐身结构的空腔中附加微穿孔板层的水下微穿孔吸声体。基于微穿孔板的精确计算理论及水下声隐身结构的特点,考虑空腔深度、穿孔板厚度、穿孔直径及穿孔率等对微穿孔板吸声性能的影响,对水下微穿孔吸声体进行了结构设计。利用脉冲声管法对水下微穿孔吸声体试样的吸声系数进行了测量,结果表明:水下微穿孔吸声体有效地拓宽了低频吸声频带,其微穿孔板结构参数的影响规律也与理论分析一致;对于多种吸声机理并存的水下微穿孔吸声体的空腔个数、形状及谐振特性等也是影响吸声性能的重要因素,在实际的工程应用中必须结合所关心的频带对水下微穿孔吸声体进行匹配优化设计。  相似文献   

5.
微穿孔板吸声结构水下应用研究   总被引:2,自引:0,他引:2       下载免费PDF全文
王泽锋  胡永明  倪明  罗洪 《应用声学》2008,27(3):161-166
马大猷教授提出的微穿孔板吸声结构在空气噪声降低和隔离方面得到了广泛的应用,但未见水下应用的相关研究和报道。本文将空气中微穿孔板理论应用到水中,得到了水下微穿孔板吸声结构的吸声公式。通过理论分析,得出了微穿孔板结构直接应用于水中无法获得宽频吸收的结论。提出了通过匹配液将微穿孔板间接应用到水下的设想。设计了单层板和双层板吸声结构,并对它们的吸声特性进行了理论分析与仿真。结果表明,本文设计的微穿孔板吸声结构在水中能够获得优于空气中的宽频带吸声效果。实验测量了自制的微穿孔板吸声结构,吸声系数的测量值与理论曲线基本吻合,从而验证了理论分析的正确性。  相似文献   

6.
管束穿孔板的管腔耦合共振吸声机理研究   总被引:1,自引:0,他引:1  
苏玉  梅中建  吕亚东  程晓斌 《声学学报》2021,46(6):1202-1211
为了揭示管束穿孔板共振吸声结构的吸声机理,利用热黏性条件下基于有限元算法的管束穿孔板仿真模型,研究了平面声波正入射条件下,管束穿孔板内部声场分布特征,并利用阻抗管对吸声系数的理论仿真结果进行了试验验证.结果表明,管束穿孔板在低频主要靠腔体共振吸声,在高频主要靠管共振吸声,管束穿孔板整体呈现出较为明显的管腔耦合共振吸声特征。管束穿孔板共振时管中声强和质点法向振速较大,高频次吸声峰频点处管中和腔中均有驻波形成,频率越高驻波数量越多.管束穿孔板的耦合共振受到管长、腔深、穿孔率和管内径等参数变化的影响,管长对高频耦合共振的影响最大,管长增大使高频主吸声峰频点移向低频,并使相邻主吸声峰之间的间距减小.   相似文献   

7.
针对单层微穿孔板的低频吸声问题提出了微穿孔板复合板型声学超材料结构。将板型声学超材料置入微穿孔板结构的背腔内部实现结构复合。实验结果表明:在相同背腔厚度下,复合结构的吸声性能整体优于单层微穿孔板结构,其中复合结构的吸声曲线从396~892 Hz均大于0.6,在453 Hz处吸声系数达到0.972。利用有限元方法对复合结构进行了仿真,仿真计算的吸声曲线与实验吸声曲线的趋势基本相同,同时发现低频吸声主要由板型声学超材料与声波相互作用贡献。板型声学超材料的吸声峰值的对应频率处,其等效动态质量密度从正变负。在复合结构内部的微穿孔板和板型声学超材料存在相互耦合作用,使得复合结构的第一峰值发生微小偏移。增加板型声学超材料的质量块重量可以使第一吸声峰值向低频移动;保持总背腔厚度不变,增加板型声学超材料的子腔厚度,也可以使第一吸声峰向低频移动。   相似文献   

8.
微穿孔板的实际极限   总被引:13,自引:3,他引:13  
马大猷 《声学学报》2006,31(6):481-484
对微穿孔板吸声器的构造和吸声特性进行了分析。曾认为低穿孔常数和孔径小可导致宽频带内的高吸声特性。为求得极限,从穿孔系数为1,孔径0.1 mm开始,因为负载声阻和吸声系数可接近1,高吸声系数的共振频率可达1000 Hz,高频率可在吸声范围之内。单片微穿孔板可否用于平常噪声控制,在宽频带内吸声较大?为了比较,半吸声带宽不适用,因为可能包括低吸声系数。建议用吸声系数0.5作为实际吸声底线,为比较微穿孔板的统一标准。更以吸声系数的频率曲线以进行详细比较。负载声阻为1(声阻等于空气特性阻抗)时,微穿孔板的吸声范围约为2.5倍频程,比常用的微穿孔板稍好。负载声阻大于1时,吸声的频率范围显著增加,有些适合宽频带高吸收的要求。将其实现可能是微穿孔板吸声器的重大发展。  相似文献   

9.
沈苏  Goran Pavi 《声学学报》2011,36(3):281-290
将微穿孔板吸声结构应用到外加旁支管路的管道声源特性测量方法中,分析和仿真了单层及双层微穿孔板及其后腔结构采用不同参数(板厚、微孔直径、穿孔率、后腔深度等)时改变管道负载声阻抗的作用和影响.研究结果表明:改变板厚、微孔直径、穿孔率、管道横截面积比等参数,可以有效地改变负载声阻;改变后腔深度及微穿孔板与主体管道之间距离,可...  相似文献   

10.
水下弹性微穿孔吸声结构吸声系数研究   总被引:1,自引:0,他引:1  
利用模态叠加法建立了水介质微穿孔板的数学模型,基于声电类比法得到其等效电路模型。研究了弹性微穿孔板和弹性背腔对垂直入射吸声系数的影响。与空气介质中的微穿孔板不同,水下微穿孔板因结构阻抗不足,难以取得满意的吸声效果,为此提出了增强型微穿孔吸声结构,并在水介质阻抗管内对理论结果予以验证。结果表明,随着增强型弹性微穿孔板弯曲刚度的增大,其在[20,2000]Hz范围内的平均吸声系数得到提高,逐步趋近于刚性微穿孔板的结果,弹性背板使微穿孔吸声结构的吸声峰向低频移动,低频吸声效果得到提高。   相似文献   

11.
Because microperforated panels (MPPs) can provide wide-band sound absorption without fibrous and porous materials, they are recognized as next-generation absorption materials. The fundamental absorbing mechanism is Helmholtz-resonance absorption due to the perforations and air-back cavity. Consequently, MPPs are usually placed in front of rigid-back walls. However, one of the authors has proposed MPP space sound absorbers without backing structures. Among these space absorbers, cylindrical MPP space absorbers and rectangular MPP space absorbers are advantageous due to their design flexibility and easy-to-use properties. Although their performances have been investigated experimentally, it is necessary to predict their absorption characteristics to develop improved shapes and efficient designs. Herein their absorption characteristics are numerically predicted using the two-dimensional boundary element method, and the applicability of a numerical method as a design tool to sufficiently predict the performance of MPP space absorbers is discussed.  相似文献   

12.
Super-aligned carbon nanotube (SACNT) arrays are grown on the surface of micro perforated panel (MPP) in the hope of improving the acoustic performance of MPP absorbers by virtue of their unique properties. Scanning electron microscopy reveals that SACNT arrays did not block the perforations of MPPs or changed the perforation diameter due to their “super-aligned” nature, although MPPs are thickened. The absorption effect of SACNT arrays which are of the same and different lengths with different incident side on MPP absorbers are investigated, and standing wave tube method is used to determine the normal sound absorption coefficient. Results show that both of the lengths of SACNT arrays and the incident side have effects on the sound absorption performance of MPP absorbers. And generally SACNT arrays help to improve the sound absorption capacity of MPP absorbers in low-frequency regions only when the SACNT arrays surface is the incident side. SACNT arrays decrease absorption performance of MPP absorbers when the MPP surface is used as the incident side. Moreover, SACNT arrays are found to increase the acoustic ability of MPP absorbers with the same structure parameters monotonically at lengths up to 600 μm in the condition that the SACNT arrays surface is used as the incident side.  相似文献   

13.
Microperforated panels (MPPs) coupled to a rigid wall have been proposed recently as an alternative to porous absorbers in situations having concerns with bacterial contamination and small particles discharge, like food, pharmaceutical and microelectronic industries. There exists also an increasing interest for MPP absorbers in the transportation industry and civil engineering. In general, an optimally designed MPP with good broadband absorption requires many submillimetric holes distributed over a panel of also submillimetric thickness. Such thin plates or foils become so fragile that they need to be protected from mechanical damage. In this paper, an alternative strategy is investigated which allows the design of MPPs with panels of millimetric thickness while maintaining their acoustic performance. These absorbers, named microperforated insertion units (MIUs), avoid the structural problems of the classical MPPs. An assessment of the sound absorption properties of these structures is presented. Comparisons between calculations and measurements are also made under two experimental conditions: plane waves at normal incidence (impedance tube) and free field (anechoic room).  相似文献   

14.
A method for evaluating the absorption and transmission performances of multi-layer micro-perforated structures whose facings are excited by different noise sources is described here. It is applied to determine if the acoustical performances of a number of Micro-Perforated Panels (MPPs), optimised both in absorption and transmission, exceed those of typical aircraft panels undergoing internal and external acoustic excitations. A fully-coupled modal formulation is presented that accounts for the effects of the sub-structure volumetric resonances on the acoustical properties of the partitions. It is validated against full-scale measurements performed with a pressure–velocity probe and a laser vibrometer to estimate the absorption and transmission coefficients of single- and double-layer micro-perforated partitions. The model is used to optimise the sound power dissipated by three layouts obtained from a typical aircraft partition by micro-perforating the trim panel (MPP–Porous–Panel), removing the fibreglass material (MPP–Cavity–Panel) and adding a second MPP inside the separating cavity (MPP–MPP–Panel). It is concluded that the MPP–Porous–Panel and MPP–MPP–Panel layouts provide excess interior noise reduction above 1.8 kHz and 1.2 kHz respectively, whereas the MPP–Cavity–Panel is not acoustically more efficient than a typical aircraft panel.  相似文献   

15.
Microperforated panel (MPP) absorbers are promising as a basis for the next-generation of sound absorbing materials. MPPs are typically made of a thin metal or plastic panel. However, thin limp panels are generally not suitable as an interior finish of room walls because they do not have sufficient strength, which prevents practical application of MPPs as an interior finish of room walls. In order to overcome the lack of appropriate strength required for room walls, it is possible to make an MPP out of a thick panel. However, thick MPPs are usually not efficient because the resistance and/or reactance become too high. In this study, trial production of thick MPPs and measurement of their normal absorption coefficients were carried out. Results show that efficient absorption can be given with a thick MPP by using a tapered perforation.  相似文献   

16.
As for the sound absorbing system using an MPP (microperforated panel), a double-leaf MPP sound absorber has been studied so far. However, this structure uses two MPPs, which are still expensive, and is disadvantageous when its cost is concerned. Therefore, it is considered that it can be advantageous if one of the leaves can be replaced with a less expensive material keeping high sound absorption performance. In this study, the possibility of producing a useful sound absorbing structure with an MPP and a permeable membrane as an alternative less expensive material is examined. The acoustic properties of this MPP and permeable membrane combination absorber are analysed theoretically with a Helmholtz integral formulation. The absorption performance and mechanism are discussed through the numerical examples. Also, the effect of a honeycomb in the air cavity, which is to be used for reinforcing the structure, is also discussed through a theoretical analysis.  相似文献   

17.
Because microperforated panels (MPPs), which can be made from various materials, provide wide-band sound absorption, they are recognized as one of the next-generation absorption materials. Although MPPs are typically placed in front of rigid walls, MPP space sound absorbers without a backing structure, including three-dimensional cylindrical MPP space absorbers (CMSAs) and rectangular MPP space absorbers (RMSAs), are proposed to extend their design flexibility and easy-to-use properties. On the other hand, improving the absorption performance by filling the back cavity of typical MPP absorbers with porous materials has been shown theoretically, and three-dimensional MPP space absorbers should display similar improvements. Herein the effects of porous materials inserted into the cavities of CMSAs and RMSAs are experimentally investigated and a numerical prediction method using the two-dimensional boundary element method is proposed. Consequently, CMSAs and RMSAs with improved absorption performances are illustrated based on the experimental results, and the applicability of the proposed prediction method as a design tool is confirmed by comparing the experimental and numerical results.  相似文献   

18.
针对普通薄膜型降噪结构的吸声性能较差和吸声带宽较窄的问题,本文设计了一种微穿孔的介电弹性体薄膜吸声结构。该结构由穿孔的介电弹性体薄膜与背腔组合而成,目的是拓宽介电弹性体薄膜低频率段的吸声带宽。针对微穿孔的介电弹性体薄膜吸声结构,从试验角度分析穿孔薄膜初始厚度、穿孔孔径及穿孔间距对结构吸声性能的影响。分析结果可知:通过适当增加薄膜的初始厚度,薄膜的整体吸声性能得到有效提升,最大可将319Hz吸声频带的吸声系数从0.2提升至0.7;减小薄膜的穿孔孔径能够有效拓宽穿孔薄膜的吸声频带,可使吸声系数0.4以上的吸声带宽由304Hz拓宽至432Hz;适当控制穿孔间距能够达到更好的吸声效果。  相似文献   

19.
A numerical study of double-leaf microperforated panel absorbers   总被引:1,自引:0,他引:1  
Microperforated panel (MPP) absorbers are promising as a basis for the next-generation of sound absorbing materials. Typically, they are backed by an air-cavity in front of a rigid wall such as a ceiling or another interior surface of a room. Indeed, to be effective, MPP absorbers require the Helmholtz-type resonance formed with the backing cavity. Towards the creation of an efficient sound-absorbing structure with MPPs alone, the acoustical properties of a structure composed of two parallel MPPs with an air-cavity between them and no rigid backing is studied numerically. In this double-leaf MPP (DLMPP) structure, the rear leaf (i.e., the MPP remote from the incident sound) plays the role of the backing wall in the conventional setting and causes resonance-type absorption. Moreover, since a DLMPP can work efficiently as an absorber for sound incidence from both sides, it can be used efficiently as a space absorber, e.g., as a suspended absorber or as a sound absorbing panel. The sound absorption characteristics of the double-leaf MPP are analysed theoretically for a normally incident plane wave. The effects of various control parameters are discussed through a numerical parametric study. The absorption mechanisms and a possible design principle are discussed also. It is predicted that: (1) that a resonance absorption, similar to that in conventional type MPP absorbers, appears at medium-to-high frequencies and (2) that considerable “additional” absorption can be obtained at low frequencies. This low-frequency absorption is similar to that of a double-leaf permeable membrane and can be an advantage compared with the conventional type of MPP arrangement.  相似文献   

20.
Multi-layer structures have issues with sound insulation at low and mid-frequencies due to mass-air-mass resonance. The purpose of this study is to investigate improvements to the sound insulation performance of multi-layer structures using a microperforated panel (MPP), which can absorb well over a wide frequency range. Although MPPs have been investigated over the last several decades, almost all studies have been conducted in terms of sound absorption. Herein the sound transmission loss of multi-layer structures with flexible MPPs of infinite extent is theoretically investigated. The calculation is based on the wave equation and the equation of panel vibration including the effect of perforation of the panel. Additionally to consider a more realistic sound insulation performance, the effect of the directional distribution of the incident energy in a reverberation chamber is taken into account. Experiments are conducted using an acoustic tube to validate the calculated results and the reverberation chamber method to verify the actual sound insulation characteristics. Both experiments agree well with the theoretically calculated perforation effects. Consequently, MMPs are confirmed to improve the deterioration of sound insulation performance due to mass-air-mass resonance of multi-layer structures.  相似文献   

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