A circular array (CA) transducer is developed and validated to implement internal inspection of the small diameter tubes, one of whose potential application targets is the heat exchanger tubes in Modular High Temperature Gas-cooled Reactor. A geometric model of the transducer and the delay law are proposed according to the inspection setup. Using k-Wave, an open source acoustic simulation toolbox, the beam profiles of various aperture sizes are analyzed to select a suitable aperture. The beams with different focal depths are compared to verify the delay law and to choose a preferable focus. Reflector responses are simulated to predict the transducer’s detection sensitivity. To validate the simulation results, a prototype transducer composed of 64 elements is fabricated. Its electrical and acoustical performances are acquired with a pulser-receiver. A 4-element aperture with the focal depth of 1.0 mm is selected to perform internal inspection experiment according to the simulation results. The eight longitudinal grooves with widths of 0.2, 0.3, 0.4, and 0.5 mm on inner and outer tube walls are applied as typical reflectors to test circumferential detection sensitivity. The other five grooves with depths from 0.1 mm to 0.5 mm are chosen to verify radial detection sensitivity. The experiment results demonstrate the detection sensitivity of the CA transducer reaches at least 0.2 mm in circumferential direction and 0.1 mm in radial direction. The CA is proven capable of inspecting small diameter tubes.

开发并验证了圆形阵列（CA）传感器以实现小直径管的内部检查，其潜在应用目标之一是模块化高温气冷堆中的换热器管。根据检测设置提出了换能器的几何模型和延迟定律。使用开源声学仿真工具箱 k-Wave 分析各种孔径尺寸的波束轮廓，以选择合适的孔径。通过比较不同焦深的光束来验证延迟定律并选择更好的焦点。模拟反射器响应以预测传感器的检测灵敏度。为了验证仿真结果，制造了由 64 个元件组成的原型传感器。其电气和声学性能是通过脉冲接收器获得的。根据仿真结果，选择焦深为1.0 mm的4元孔径进行内部检测实验。采用内外管壁上宽度分别为0.2、0.3、0.4、0.5 mm的8条纵向凹槽作为典型反射器，测试周向检测灵敏度。选择其他5个深度为0.1毫米至0.5毫米的凹槽来验证径向检测灵敏度。实验结果表明，CA传感器的检测灵敏度在圆周方向至少达到0.2 mm，在径向方向至少达到0.1 mm。事实证明，CA 能够检查小直径管。