共查询到19条相似文献,搜索用时 46 毫秒
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将阻性管道消声器消声量特征方程(组)转化为常微分方程(组),由此给出消声量计算的一个新方法。该方法毋需迭代因而不存在计算稳定性问题,计算量小,初值的迭取也很简单,适合于扁矩形、任意矩形及圆形等各种截面管道消声器,尤其对多变量、考虑平均流影响的情形更为有效。 相似文献
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为了获得运动型排气噪声,本文研究了汽车排气系统消声器结构对运动声学品质的影响。通过改变消声器的内部结构,建立与之对应的GT-Power模型,利用一维流体动力学原理对排气系统的声学性能进行模拟和仿真,并运用声学测试平台测试节气门全开加速时的尾管噪声。验证了去除排气系统的中排消声器并在后排消声器内加入消声棉的结构,可明显提高噪声的运动性,另外,消音棉的利用可以有效降低高频噪声,消声器进气管处的穿孔结构可以有效消除中低频噪声。 相似文献
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本文以实现汽车排气消声器的正向设计为目的,提出消声器的开发思路:首先采用从分析设计目标到确定总体方案,再到具体设计的路线,结合Virtual.Lab Acoustics、GT-Power和Fluent等数值分析软件与发动机台架试验。然后以主消声器的设计为主,副消声器的设计为辅;以声学性能为主,流场及其他性能为辅。再通过对消声频率的分析,逐级设计消声结构并进行组合、验证和改进,并在与企业提供的消声器方案进行对比后初步判断设计方案的可行性。最后通过实验验证了消声器设计方案的综合性能达到设计目标,表明了本文提出的消声器正向开发思路的合理性,在汽车排气消声器的设计开发上具有实用价值。 相似文献
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本文以虹吸式座便器为研究对象,将扩张室消声器应用于座便器管道结构设计中,采用CFD (computational Fluid Dynamics)软件对加装不同长度扩张室消声器的座便器模型进行了冲水过程数值模拟。在研究座便器噪声产生机理及扩张室消声器声学性能的基础上,进行座便器冲洗性能试验及噪声测量试验,分别研究了冲水量与冲洗噪声、冲水量与冲洗性能之间的关系。研究表明,安装扩张室消声器,不仅可以提高座便器的冲洗性能,还可以降低冲洗噪声,达到降噪节水的目的。 相似文献
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Low frequency noise in duct is a challenge for the traditional passive noise control techniques. Recently, a so-called duct-membrane silencer has attracted much research attention due to its simple configuration and potential application, however, the current studies are merely limited to the cases in which just the classical boundary conditions are considered. Actually, as an important factor affecting the modal characteristics of the membrane, and the existing studies are not enough to fully understand the vibro-acoustic characteristics of such silencer with complicated boundary conditions. Motivated by this, in this paper, the structural–acoustic coupling model of duct-membrane system is established by a modified Fourier series method in combination with Rayleigh–Ritz procedure, in which the transverse elastic boundary restraints are taken into account. Energy principle is formulated for the vibro-acoustic coupling of such duct-membrane silencer to obtain the system matrix equation. Numerical results are then presented to validate the proposed model, and the influence of boundary restraining stiffness on sound attenuation performance is also studied. To the best of authors’ knowledge, this work represents the first time that the elastic boundary restraints have been considered for such duct-membrane silencing system. 相似文献
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I.IntroductionAcousticshockwavcs(ASW)isanimportantphcnomcnoninnonlinearacoustics.Experimentalrcsultshavcshownthatwhenanaircraftcngincinletopcratesneartheson-iccondition,vcrystrongnoisegcncratedbythcfanscanbcreduccdgreat1yowingtothcformationofASWatthcthroatofthcin1etll].ASWisadiscontinuityofacousticvaria-bles,whichisdifTcrcntfromthcshockwavesoccurringinhighspcedsteadyflowinducts.Theformer'sintensityismuch1cssthanthelattcr's.Furthcrmorc,thepositionandintensityofASWisalwayschangedwithtime.l… 相似文献
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本文从应用角度,对片式消声器的结构,消声机理,设计原则等作了较为全面的阐述,介绍了应用实例,结合工程实践,提出了一个估算存在气流时消声系数的经验公式。 相似文献
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针对含噪语音难以实现有效的语音转换,本文提出了一种采用联合字典优化的噪声鲁棒性语音转换算法。在联合字典的构成中,语音字典采用后向剔除算法(Backward Elimination algorithm,BE)进行优化,同时引入噪声字典,使得含噪语音与联合字典相匹配。实验结果表明,在保证转换效果的前提下,后向剔除算法能够减少字典帧数,降低计算量。在低信噪比和多种噪声环境下,本文算法与传统NMF算法和基于谱减法消噪的NMF转换算法相比具有更好的转换效果,噪声字典的引入提升了语音转换系统的噪声鲁棒性。 相似文献
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The object of this work is to establish a general approach that can analyze the performance of most of the silencers with/without sound absorbent material. Under the assumption of plane wave propagation, the transfer matrices between the two ends of straight pipe and two-duct perforated section are derived and taken as the basic elements. Based on the conditions of continuity of pressure and of mass velocity, the silencer is modeled as a network formed by the two basic elements. Then the sound attenuation characteristic of the silencers can be investigated. With this scheme the multiply connected acoustic filters can also be analyzed. Further, the porous sound absorbent material is also included in this scheme. The effect of sound absorption material on the performance of silencers is analyzed and discussed. 相似文献
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S.N. Panigrahi 《Applied Acoustics》2007,68(6):660-681
Commercial automotive mufflers are often too complex to be broken into a cascade of one-dimensional elements with predetermined transfer matrices. The one-dimensional (1-D) scheme presented in this paper is based on an algorithm that uses user-friendly visual volume elements along with the theory of transfer matrix based muffler analysis. This work attempts to exploit the speed of the one-dimensional analysis with the flexibility, generality and user-friendliness of three-dimensional analysis using geometric modeling. A code based on the developed algorithm has been employed to demonstrate the generality of the proposed method in analyzing commercial mufflers by considering three very diverse classes of mufflers with different kinds of combinations of reactive, perforated and absorptive elements. Though the examples used in the paper are not very complex for they are meant to be just representative cases of certain classes of mufflers, yet the algorithm can handle a large domain of commercial mufflers of high degree of complexity. Results from the present algorithm have been validated through comparisons with both the analytical (plane wave based) and the more general, three-dimensional FEM based results. The forte of the proposed method is its power to construct the system matrix consistent with the boundary conditions from the geometrical model to evaluate the four-pole parameters of the entire muffler and thence its transmission loss, etc. Thus, the algorithm can be used in conjunction with the transfer matrix based muffler programs to analyze the entire exhaust system of an automobile. 相似文献
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针对气流通道彼此独立且截面尺寸较小的直管式阻性消声器,Belov基于声波导管理论推导了其消声量计算公式,但该公式不适用于气流通道彼此连通且截面尺寸较大的阵列式阻性消声器。为此,提出了一种阵列式消声器消声量计算方法。将阵列式消声器划分为周期性排列的消声单元,每个消声单元包含1个吸声柱。分别参照扩张式消声器和直管阻性消声器计算消声单元的抗性部分(进出口气流通道截面突变处)和阻性部分消声量的理论值TL1和TL2。在此基础上,采用有限元法仿真得到消声器消声量仿真值TLs,基于阻性部分消声量仿真值和理论值的比值(TLs-TL1)/TL2,拟合确定各倍频带阻性消声量修正函数Nf,即修正后的消声量理论值计算模型为TL′t=TL1+TL2·Nf。作为算例,建立了多孔吸声材料流阻率为11425 Pa·s/m2时适用于不同结构尺寸的阵列式消声器消声量计算模型。实测结果... 相似文献