Empirical model of the acoustic impedance of a circular orifice in grazing mean flow.
Empirical model of the acoustic impedance of a circular orifice in grazing mean flow.
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DOI：
10.1121/1.1581280
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发表时间：
2003-07
期刊：
影响因子：
--
通讯作者：
Seong-Hyun Lee;J. Ih
中科院分区：
文献类型：
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作者：
Seong-Hyun Lee;J. Ih
虽然孔板声阻抗的理论模型和经验模型很多，但在某些情况下，采用其中任何一种模型预测的声学性能与实测结果有很大的差异。为了获得一个新的实用和精确的经验阻抗模型在掠流条件下，圆孔声阻抗已被测量与非常仔细的测试和控制的测量条件下的有关参数的变化。确定孔板声阻抗的参数包括孔板直径、孔板厚度、穿孔率、平均流速和频率。所涉及的参数的范围被选择为覆盖内燃机的典型排气系统中的穿孔的实际数据跨度。通过对各种参数测试结果进行非线性回归分析，得到了经验阻抗模型。所提出的经验模型的孔阻抗，具有很高的相关系数，适用于同心谐振器，这具有典型的声学短和长通流谐振器的几何配置的传输损耗的预测。通过比较测量结果和预测结果，其中预测是通过采用许多以前的孔板阻抗模型以及本模型，它被证实，建议的孔板阻抗模型产生最准确的预测在所有其他现有的阻抗模型。
Although there are many analytical and empirical models for orifice impedance, the predicted acoustical performance when adopting any one of them sometimes shows a large discrepancy with the measured result in some cases. In order to obtain a new practical and precise empirical impedance model under grazing flow conditions, the acoustic impedance of circular orifices has been measured with a variation of the involved parameters under very carefully tested and controlled measurement conditions. The parameters involved in determining the acoustic impedance of an orifice are comprised of the orifice diameter, orifice thickness, perforation ratio, mean flow velocity, and frequency. The range of involved parameters is chosen to cover the practical data span of perforates in typical exhaust systems of internal combustion engines. The empirical impedance model is obtained by using nonlinear regression analysis of the various results of the parametric tests. The proposed empirical model of orifice impedance, with a very high correlation coefficient, is applied to the prediction of the transmission loss of concentric resonators, which have geometric configurations typical of acoustically short and long through-flow resonators. By comparing the measured and predicted results, in which the predictions are made by employing many previous orifice impedance models as well as the present model, it is confirmed that the proposed orifice impedance model yields the most accurate prediction among all other existing impedance models.