Park Chul-Min, Ih Jeong-Guon, Nakayama Yoshio, Takao Hideo
Center for Noise and Vibration Control, Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, Science Town, Taejon 305-701, Korea.
J Acoust Soc Am. 2003 Jan;113(1):128-38. doi: 10.1121/1.1526664.
A porous tube, comprised of a resin-coated woven fabric has recently been used as an effective component for use in intake systems of internal combustion engines to reduce the intake noise. For the prediction of the acoustic performance of an engine intake system with a porous woven hose, the acoustic wall impedance of the hose must be known. However, the accurate measurement of the wall impedance of a porous woven hose is not easy because of its peculiar acoustical and structural characteristics. A new measurement technique is proposed herein, that is valid over the low to mid frequency ranges. The acoustics impedance is inversely estimated from an overdetermined set of measured pressure transmission coefficients for specimens of different lengths and the reflection coefficient of end termination. The method involves only one measurement setup, and, as a result, it is very simple. A variation of the proposed method, an inverse estimation method using one of the four-pole parameters is also proposed. An error sensitivity analysis was performed to investigate the effect of measurement error on the accuracy of the final result. The measured TL for samples with arbitrary lengths and arbitrary porous frequency are in reasonably good agreement with values predicted from curve-fitted impedance data.
一种由树脂涂层织物制成的多孔管最近被用作内燃机进气系统中的有效部件，以降低进气噪声。为了预测带有多孔编织软管的发动机进气系统的声学性能，必须知道软管的声壁阻抗。然而，由于多孔编织软管独特的声学和结构特性，准确测量其壁阻抗并非易事。本文提出了一种新的测量技术，该技术在低至中频范围内有效。根据不同长度试样的一组超定测量压力传输系数和端接反射系数来反演声阻抗。该方法只涉及一个测量装置，因此非常简单。还提出了该方法的一种变体，即使用四极参数之一的反演估计方法。进行了误差敏感性分析，以研究测量误差对最终结果准确性的影响。任意长度和任意多孔频率样品的测量传输损失与根据曲线拟合阻抗数据预测的值相当吻合。
