Abstract

Using the example of an integrated airframe, we performed a computational and experimental study of the possibility of using geometric diffraction theory (GDT) to calculate the sound diffraction when the airframe is replaced with simulating flat polygonal screen as pertains to the effectiveness of noise screening of aircraft power plants. We compared (1) impulse responses experimentally measured with maximum length sequences and the reciprocity theorem for both a three-dimensional model of the airframe and its plane model with (2) the responses calculated using GDT; the results showed good qualitative agreement for observation points in the geometric shadow zone and in the illuminated area, as well as quantitative coincidence in the frequency range characteristic of jet noise and the first harmonics of the blade passing frequency of a propeller or fan.

中文翻译：

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利用几何衍射理论研究用平面多边形筛网代替一体式机体以估计发动机噪声筛查效率的可能性的研究

摘要

以一体式飞机机身为例，我们进行了计算和实验研究，探讨了用几何衍射理论（GDT）计算机身替代模拟平面多边形屏幕代替飞机机身时的声音衍射的可能性，这涉及到噪声屏蔽的有效性。飞机发电厂。我们将（1）用最大长度序列实验测量的冲激响应和机身三维模型及其平面模型的互易定理与（2）使用GDT计算的响应进行了比较；结果表明，在几何阴影区域和照明区域中的观察点具有良好的定性一致性，