A new type of the acoustic black hole beam—a helix-acoustic black hole—is proposed to overcome the spatial restriction on modular acoustic black hole structures. The modular acoustic black hole structure, consisted of a base and several number of acoustic black hole beams, has potential to apply into real engineering world. There are two main sections in an acoustic black hole beam: (1) a uniform thickness part and (2) an acoustic black hole region of which the thickness decreases according to the power-law profile. Conventional acoustic black hole beams can be ultimately assembled as 8–10 acoustic black hole beams on a modular acoustic black hole structure. In this article, a different shape of an acoustic black hole beam is newly designed to allow the assembly of more acoustic black hole beams on the modular acoustic black hole structure. The shape of the helix-acoustic black hole is such that the thickness of the acoustic black hole region smoothly decreases, just like a conventional acoustic black hole beam, as well as twisting along the longitudinal direction. The normal direction of the bottom surface in the uniform thickness is the same along the longitudinal axis in the conventional acoustic black hole beam. However, the normal direction of the helix-acoustic black hole of the bottom surface in the acoustic black hole region is different along the longitudinal direction. It is necessary to use numerical simulations to explore the performance of the helix-acoustic black hole beam because the shape of acoustic black hole region is different from the conventional one. Two types of numerical simulations were conducted: transient analysis and modal frequency analysis. From the transient analysis, the acoustic black hole effect was investigated by comparing the travel time which is dependent on the variation of the thickness. Using modal frequency analysis, the reflection coefficients between the conventional acoustic black hole beam and helix-acoustic black hole beam are also compared. It is noted that reflection coefficients were additionally compared depending on how “sharply” or “smoothly” they were twisted in the acoustic black hole region of the helix-acoustic black hole. Those results demonstrate that the helix-acoustic black hole has a dynamic characteristic similar to that of conventional acoustic black hole beams, which means that more helix-acoustic black holes can be assembled on the modular acoustic black hole structure by resolving the spatial restriction and leading to expectations of better performance.

为了克服模块化声学黑洞结构的空间限制，提出了一种新型的声学黑洞束（螺旋声黑洞）。模块化的声学黑洞结构由一个基座和多个声学黑洞束组成，有潜力应用于实际工程领域。声黑洞光束中有两个主要部分：（1）厚度均匀的部分；（2）声黑洞区域，其厚度根据幂律轮廓而减小。常规的声学黑洞波束最终可以作为8–10个声学黑洞波束组装在模块化声学黑洞结构上。在本文中，新设计了一种不同形状的声学黑洞束，以允许在模块化声学黑洞结构上组装更多的声学黑洞束。螺旋声学黑洞的形状使得声学黑洞区域的厚度像常规声学黑洞束一样平滑地减小，并且沿着纵向方向扭曲。底面的法线方向的厚度均匀，与以往的声黑孔波束的纵轴相同。然而，在声学黑洞区域中，底表面的螺旋声学黑洞的法线方向沿着纵向方向是不同的。由于声学黑洞区域的形状不同于传统的声学黑洞区域的形状，因此有必要使用数值模拟来探索螺旋声学黑洞束的性能。进行了两种类型的数值模拟：瞬态分析和模态频率分析。通过瞬态分析，通过比较取决于厚度变化的传播时间，研究了声学黑洞效应。使用模态频率分析，还比较了常规声黑洞光束和螺旋声黑洞光束之间的反射系数。要注意的是，还根据反射系数在螺旋声黑洞的声学黑洞区域中被扭曲的角度“尖锐”或“平滑”进行了比较。这些结果表明，螺旋声黑洞具有与常规声黑洞束类似的动态特性，