消声器声学性能计算的数值模态匹配法

发布时间：2018-04-25 15:40

本文选题：消声器 + 数值模态匹配法　；参考：《哈尔滨工程大学》2014年博士论文

【摘要】：消声器广泛应用于内燃机进排气噪声控制,其声学特性的计算与分析是消声器设计的基础。三维解析方法只适用于计算横截面形状规则的消声器的声学性能;数值方法不受几何形状限制,可以计算任意形状消声器的声学特性,但是对于高频性能的计算,数值方法受网格尺寸以及计算机性能的限制。鉴于此,本文研究数值模态匹配法用于计算和分析任意形状横截面的消声器的声学特性。论文介绍了应用数值模态匹配法计算消声器内部三维声场问题的基本过程,将二维有限元法应用于求解消声器的横向模态,使用模态匹配法求解消声器的传递损失。应用数值模态匹配法计算并分析了膨胀腔消声器、穿孔管消声器以及有流消声器的声学性能。将数值模态匹配法计算结果分别与三维有限元法计算结果以及实验测量结果进行对比,验证了数值模态匹配法以及计算程序的正确性。比较了数值模态匹配法和三维有限元方法的计算时间,证明了数值模态匹配法的优越性。进而应用数值模态匹配法研究了消声器结构参数、填充材料、均匀流以及高阶模态对消声器声学特性的影响,从模态的角度研究了消声器声学性能优化方法。将消声器进出口管布置于高阶模态的节线上,可以抑制该阶模态的激发,从而拓宽消声器的消声频带。减小穿孔管孔径或增大穿孔率,可以使穿孔管抗性和阻性消声器模态激发频率变高,进而提高消声器中高频消声性能。消声器内部填充吸声材料的密度越大,穿孔管消声器的整体消声效果越好。均匀流马赫数越大,穿孔管抗性消声器在中高频的消声量越高,而阻性消声器在整个频带内的消声性能越差。对于复杂结构消声器,提出了基于子域划分的耦合处理方法。其基本思想是:将复杂结构消声器划分成儿个子域,利用三维方法求解各个子域的传递矩阵或者阻抗矩阵,结合各个子域在公共交界面上的连续性条件,求解消声器的整体传递矩阵和阻抗矩阵,进而计算得到其传递损失。使用耦合处理方法计算双腔消声器的传递损失,并且与三维有限元计算结果进行对比,验证该方法的正确性。为了验证本文所提出的数值模态匹配法预测消声器声学性能的正确性,利用声波分解法和两负载法测量了无流状态下两种穿孔管消声器的传递损失,实验测量结果与本文方法计算结果吻合良好,表明本文所开发的数值模态匹配法预测程序和实验测量方法是正确的。
[Abstract]:Muffler is widely used in internal combustion engine intake and exhaust noise control. The calculation and analysis of its acoustic characteristics is the basis of muffler design. The three-dimensional analytical method can only be used to calculate the acoustic performance of the muffler with regular cross-section shape. The numerical method is not restricted by geometric shape and can be used to calculate the acoustic characteristics of the muffler with arbitrary shape, but the high frequency performance can be calculated. Numerical methods are limited by mesh size and computer performance. In view of this, the numerical modal matching method is used to calculate and analyze the acoustic characteristics of silencers with arbitrary cross section. This paper introduces the basic process of using numerical modal matching method to calculate the three-dimensional sound field problem in muffler. The two-dimensional finite element method is applied to solve the transverse mode of muffler, and the modal matching method is used to solve the transfer loss of muffler. The acoustic properties of expansion cavity muffler, perforated tube muffler and flow muffler are calculated and analyzed by numerical modal matching method. The results of numerical modal matching method are compared with the results of 3D finite element method and experimental measurement, and the correctness of the numerical modal matching method and the calculation program are verified. The computational time of the numerical modal matching method and the three-dimensional finite element method are compared, and the superiority of the numerical modal matching method is proved. Furthermore, the effects of structural parameters, filling materials, uniform flow and high order modes on the acoustic characteristics of muffler are studied by using numerical modal matching method. The optimization method of acoustic performance of muffler is studied from the viewpoint of modal. The silencer inlet and outlet tube is arranged on the nodal line of high order mode, which can restrain the excitation of the order mode and widen the muffler's frequency band. Reducing the aperture of perforated tube or increasing the perforation rate can increase the modal excitation frequency of the perforated tube resistant and resistive muffler and then improve the high frequency silencing performance of the muffler. The greater the density of the sound-absorbing material in the muffler, the better the overall silencing effect of the perforated tube muffler. The larger the Mach number of uniform flow is, the higher the noise suppression rate of perforated tube resistant muffler is at the middle and high frequency frequency, and the worse the noise attenuation performance of the resistive muffler is in the whole frequency band. For the muffler with complex structure, a coupling processing method based on subdomain partition is proposed. The basic idea of this method is to divide the muffler into child subdomains, to solve the transfer matrix or impedance matrix of each subdomain by using three-dimensional method, and to combine the continuity conditions of each subdomain on the common interface. The global transfer matrix and impedance matrix of muffler are solved, and the transfer loss is calculated. The coupling processing method is used to calculate the transfer loss of the dual-cavity muffler and the results are compared with the results of three-dimensional finite element method to verify the correctness of the method. In order to verify the correctness of the numerical modal matching method proposed in this paper to predict the acoustic performance of the muffler, the transfer loss of two perforated tube mufflers under the condition of no flow is measured by using the acoustic decomposition method and the two-load method. The experimental results are in good agreement with the calculated results, which shows that the numerical modal matching method developed in this paper is correct.
【学位授予单位】：哈尔滨工程大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TB535.2

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