Acoustic Technology, Department of Electrical Engineering, Technical University of Denmark Building 352, Ørsteds Plads, DK-2800 Kongens Lyngby, Denmark.
J Acoust Soc Am. 2012 Jan;131(1):186-93. doi: 10.1121/1.3662052.
This paper proposes and examines a direct formulation in space domain of the so-called supersonic acoustic intensity. This quantity differs from the usual (active) intensity by excluding the circulating energy in the near-field of the source, providing a map of the acoustic energy that is radiated into the far field. To date, its calculation has been formulated in the wave number domain, filtering out the evanescent waves outside the radiation circle and reconstructing the acoustic field with only the propagating waves. In this study, the supersonic intensity is calculated directly in space domain by means of a two-dimensional convolution between the acoustic field and a spatial filter mask that corresponds to the space domain representation of the radiation circle. Therefore, the acoustic field that propagates effectively to the far field is calculated via direct filtering in space domain. This paper presents the theory, as well as a numerical example to illustrate some fundamental principles. An experimental study on planar radiators was conducted to verify the validity of the technique. The experimental results are presented, and serve to illustrate the usefulness of the analysis, its strengths and limitations.
本文提出并检验了一种在空间域中对所谓的超声声强的直接表述。与通常的（主动）强度不同，这种强度排除了声源近场中的循环能量，提供了一个辐射到远场的声能量图。迄今为止，它的计算已经在波数域中进行了表述，过滤掉了辐射圆外的消逝波，并仅用传播波来重建声场。在这项研究中，通过在空间域中对声场和空间滤波器掩模进行二维卷积，直接在空间域中计算超声强度，该空间滤波器掩模对应于辐射圆的空间域表示。因此，通过在空间域中直接滤波来计算有效地传播到远场的声场。本文介绍了理论，以及一个数值示例来说明一些基本原理。还进行了平面辐射器的实验研究，以验证该技术的有效性。给出了实验结果，这些结果说明了该分析的有用性、其优势和局限性。
