IEEE Trans Ultrason Ferroelectr Freq Control. 2022 Aug;69(8):2555-2568. doi: 10.1109/TUFFC.2022.3186170. Epub 2022 Jul 29.
Common clamp-on ultrasonic flow meters consist of two single-element transducers placed on the pipe wall. Flow speed is measured noninvasively, i.e., without interrupting the flow and without perforating the pipe wall, which also minimizes safety risks and avoids pressure drops inside the pipe. However, before metering, the transducers have to be carefully positioned along the pipe axis to correctly align the acoustic beams and obtain a well-calibrated flowmeter. This process is done manually, is dependent on the properties of the pipe and the liquid, does not account for pipe imperfections, and becomes troublesome on pipelines with an intricate shape. Matrix transducer arrays are suitable to dynamically steer acoustic beams and realize self-alignment upon reception, without user input. In this work, the design of a broadband 37×17 matrix array (center frequency of 1 MHz) to perform clamp-on ultrasonic flow measurements over a wide range of liquids ( c=1000-2000 m/s, α ≤ 1 dB/MHz · cm) and pipe sizes is presented. Three critical aspects were assessed: efficiency, electronic beam steering, and wave mode conversion in the pipe wall. A prototype of a proof-of-concept flowmeter consisting of two 36-element linear arrays (center frequency of 1.1 MHz) was fabricated and placed on a 1-mm-thick, 40-mm inner diameter stainless steel pipe in a custom-made flow loop filled with water. At resonance, simulated and measured efficiencies in water of the linear arrays compared well: 0.88 and 0.81 kPa/V, respectively. Mean flow measurements were achieved by electronic beam steering of the acoustic beams and using both compressional and shear waves generated in the pipe wall. Correlation coefficients of between measured and reference flow speeds were obtained, thus showing the operational concept of an array-based clamp-on ultrasonic flowmeter.
常见的夹式超声流量计由两个放置在管壁上的单元素换能器组成。流速是通过非侵入式测量的，即不中断流量，也不穿孔管壁，这也最大限度地降低了安全风险，并避免了管内的压降。然而，在测量之前，换能器必须沿着管道轴小心定位，以正确对准声束并获得校准良好的流量计。这个过程是手动完成的，取决于管道和液体的特性，不考虑管道的不完美之处，并且在形状复杂的管道上变得麻烦。矩阵换能器阵列适用于动态引导声束并在接收时实现自对准，而无需用户输入。在这项工作中，设计了一个宽带 37×17 矩阵阵列（中心频率为 1MHz），以在广泛的液体（ c=1000-2000m/s，α ≤ 1dB/MHz·cm）和管道尺寸范围内执行夹式超声流量测量。评估了三个关键方面：效率、电子波束转向和管壁中的波模式转换。制造了一个由两个 36 元素线性阵列（中心频率为 1.1MHz）组成的概念验证流量计的原型，并将其放置在一个定制的流量回路中的 1mm 厚、40mm 内径不锈钢管上，该回路中充满了水。在共振时，线性阵列在水中的模拟和测量效率进行了很好的比较：分别为 0.88 和 0.81kPa/V。通过电子波束转向声束并使用在管壁中产生的压缩波和剪切波来实现平均流速测量。获得了测量和参考流速之间的相关系数，从而展示了基于阵列的夹式超声流量计的工作概念。
