共查询到20条相似文献,搜索用时 171 毫秒
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依据有限元方法的基本物理思想,在某些不需要计算辐射声场的准确声学参数和波束特性的工程应用方面,对流体模型进行充分简化,提出了简化模型处理的有效方法,利用该方法对超声换能器进行模拟分析,并进行了样品的制作和测试,实测结果与模型简化分析处理的结果基本一致。可以证明,用该方法进行换能器的优化设计是可行和高效的。 相似文献
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针对起伏海面高频声散射计算问题,提出了一种改进的基尔霍夫(Kirchhoff)近似方法。该方法考虑了海面的阴影区和亮区之间的多次散射声场,可对小入射角下大粗糙度起伏海面的散射声场进行计算。以一维余弦和高斯谱海面散射声场的有限元计算结果为标准解验证了所提方法的准确性和适用性。利用该方法计算了一维余弦海面的散射强度,分析了不同入射声波频率和角度下海面散射强度的分布情况,并解释了Bragg散射的产生机理,同时讨论了不同海面均方根高度和相关长度情况下高斯谱海面散射强度的变化规律。 相似文献
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传统的消声器声学性能计算和实验测量都是在消声器进出口管道作为平面波声场的条件下进行,当进出口管道内出现有高阶模态激发的三维声场时,这些计算方法和实验测量方法就不再适用。由此,采用消声器进出口管道内加径向隔板的方法来计算消声器的声学性能,当原来管道声场中出现高阶模态时,仍然可以用平面波方法计算消声器的传递损失。应用该方法对进气滤清消声器进行传递损失数值计算,在原来进出口管道的平面波声场范围内,计算结果与传统方法计算结果均接近实验的测量结果,验证了该方法预测消声器声学性能的可行性。进而在所设计的消声器中频声学性能实验测试台架上,用声波分解法对阻性消声器进行传递损失测试,实验测量结果和有限元仿真结果也吻合良好。 相似文献
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在实验室环境下精准再现基于测试或仿真的声环境,对降噪优化设计与声品质评价研究具有重要意义。常用的基于扬声器阵列的声场再现方法能在特定的空间区域内再现原始声场分布,提供更为真实的临场感和沉浸感,但扬声器的指向性特性较差会降低声场再现的精度。本文提出一种考虑扬声器指向性补偿的声场再现方法用于提高声场再现的精度。该方法基于扬声器指向性的声压表达模型,利用坐标变换的方法将空间观测点转换到以扬声器为中心的局部坐标系下,并采用插值的方法实现空间观测点的指向性补偿;最后采用声压匹配的方法求解扬声器驱动权重,实现声场的精准再现。开展基于仿真指向性补偿和实测指向性补偿的声场再现试验,结果表明考虑指向性补偿比不考虑补偿的声场再现精度平均提高了约22.37%,验证了所提声场再现方法的有效性。 相似文献
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《振动与冲击》2016,(12)
提出一种识别水下弹性结构内部激励力源的匹配场处理方法,建立基于辐射声场的广义拷贝场概念,并提出采用粒子群模拟退火融合搜索算法对最优力源强度进行匹配搜索。以水下自由声场中的单层圆柱壳体作为研究对象,对声压传递函数进行了数值计算,针对激励力源识别匹配场处理方法进行了数值仿真分析;在消声水池中进行了水下单层圆柱壳体结构振动与辐射声场测试,将测试结果与拷贝场进行匹配处理,搜索最优力源强度,并以该搜索结果进行了圆柱壳体辐射噪声预报。仿真结果与试验结果均表明,这种方法可以有效的针对结构内部的力源强度进行分析排序;同时,利用匹配识别的结果进行辐射噪声预报时,预报精度很高。 相似文献
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针对水泵的空间噪声,在结构有限元分析的基础上,提出了一种计算水泵在流体脉动压力下辐射声场的方法.考虑流体诱导产生的脉动压力,通过有限元分析计算出泵体表面的振动速度分布,采用直接边界元的方法,计算空间的辐射噪声.这种计算方法可以用来预估水泵的空间辐射噪声声场,具有一定的工程意义. 相似文献
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为研究声速法接收信号幅值的变化对温度场重建的影响,基于声学测温法开展了热校准风洞模拟试验,成功模拟了航空发动机燃烧室出口的温度场重建。首先从接收到的信号数据中提取特征,建立特征矩阵,用以反馈信号幅值的变化;然后,基于采集到的信号数据,通过最小二乘法进行温度场重建;最后,通过比对不同特征矩阵下温度场重建的实际效果,分析声速法采集的信号幅值的变化对温度场重建的影响。通过试验验证可知:接收信号幅值越大,重建温度场的均方根误差越大,当幅值大于理论值40%时,均方根误差大于理论值14.38%;接收信号幅值越小,重建温度场的最大相对误差越大,当幅值小于理论值40%时,最大相对误差大于理论值44.3762 K。本文的研究对推动声学测温技术在航空发动机燃烧室出口温度场测试领域的发展起到促进作用,具有重要技术借鉴价值。 相似文献
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《IEEE sensors journal》2009,9(12):1778-1783
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L. Duggen N. Lopes M. Willatzen H.-G. Rubahn 《International Journal of Thermophysics》2011,32(4):774-785
The finite-element method (FEM) is used to simulate the photoacoustic signal in a cylindrical resonant photoacoustic cell.
Simulations include loss effects near the cell walls that appear in the boundary conditions for the inhomogeneous Helmholtz
equation governing the acoustic pressure. Reasonably good agreement is obtained between theoretical results and experimental
data. However, it was anticipated that loss mechanisms other than viscous and thermal boundary losses occur and should be
included. Nevertheless, the feasibility to use FEM together with the derived boundary conditions to simulate the photoacoustic
signal was demonstrated and good agreement with experiments for the actual resonance frequency and the quality factor of the
cell was obtained despite its complicated geometry. 相似文献
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豪华大客车车内声场的模态分析 总被引:1,自引:0,他引:1
结合典型豪华大客车采用有限元法进行了车内声场的模态分析.文中对内部纯流体声场,考虑座椅影响和考虑声场与车身结构之间耦合作用这三种情况分别建立了车内部声场的三维有限元计算模型,并对车内声场进行了声学的模态分析. 相似文献
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S. Schneider 《International journal for numerical methods in engineering》2008,76(13):2137-2156
In this paper, a finite element (FE)/fast multipole boundary element (FMBE)‐coupling method is presented for modeling fluid–structure interaction problems numerically. Vibrating structures are assumed to consist of elastic or sound absorbing materials. An FE method (FEM) is used for this part of the solution. This structural sub‐domain is embedded in a homogeneous fluid. The case where the boundary of the structural sub‐domain has a very complex geometry is of special interest. In this case, the BE method (BEM) is a more suitable numerical tool than FEM to account for the sound propagation in the homogeneous fluid. The efficiency of the BEM is increased by using FMBEM. The BE‐surface mesh required is directly generated by the FE‐mesh used to discretize the structural sub‐domain and the absorbing material. This FE/FMBE‐coupling method makes it possible to predict the effects of arbitrarily shaped absorbing materials and vibrating structures on the sound field in the surrounding fluid numerically. The coupling method proposed is used to study the acoustic behavior of the lining of an anechoic chamber and that of an entire anechoic chamber in the low‐frequency range. The numerical results obtained are compared with the experimental data. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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Determination of the shear impedance of viscoelastic liquids using cylindrical piezoceramic resonators 总被引:1,自引:0,他引:1
Kiełczyński P Pajewski W Szalewski M 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2003,50(3):230-236
In this paper, a new method for determining the rheological parameters of viscoelastic liquids is presented. To this end, we used the perturbation method applied to shear vibrations of cylindrical piezoceramic resonators. The resonator was viscoelastically loaded on the outer cylindrical surface. Due to this loading, the resonant frequency and quality factor of the resonator changed. According to the perturbation method, the change in the complex resonant frequency /spl Delta/~/spl omega/ = /spl Delta/w/sup re/ + j/spl Delta//spl omega//sup im/ is directly proportional to the specific acoustic impedance for cylindrical waves Zc of a viscoelastic liquid surrounding the resonator, i.e., /spl Delta/~w /spl sim/ jZ/sub c/, where j = (-1)/sup 1/2/. Hence, the measurement of the real and imaginary parts of the complex resonant frequency determines the real part, R/sub c/, and imaginary part, X/sub c/, of the complex acoustic impedance for cylindrical waves Z/sub c/ of an investigated liquid. Further-more, the specific impedance Z/sub L/ for plane waves was related to the specific impedance Z/sub c/ for cylindrical waves. Using theoretical formulas established and the results of the experiments performed, the shear storage modulus /spl mu/ and the viscosity /spl eta/ for various liquids (e.g., epoxy resins) were determined. Moreover, the authors derived for cylindrical resonators a formula that relates the shift in resonant frequency to the viscosity of the liquid. This formula is analogous to the Kanazawa-Gordon formula that was derived for planar resonators and Newtonian liquids. 相似文献