电磁超声导波在管道中螺旋向传播的机理研究

Research on spiral propagation mechanism of electromagnetic ultrasonic guided wave in pipeline

为了实现电磁超声导波对管道中不同方向裂纹缺陷的有效检测,研究了超声导波螺旋向传播的机理,设计了用于管道斜向裂纹缺陷检测的电磁超声螺旋向导波换能器。基于毕奥萨伐尔定律,建立了螺旋向导波换能器等效闭合线圈的数学模型;推导分析了电磁超声螺旋向导波换能器的磁感应强度与螺旋向导波主声束传播方向的关系;实验验证了不同角度的螺旋向导波传播机理与相应的裂纹缺陷检测能力。结果表明,电磁超声螺旋向导波主声束传播方向与线圈工作导线垂直,改变换能器线圈螺旋角度可控制电磁超声导波在管道中的传播方向,线圈螺旋角度不同的换能器可实现管道中不同斜向角度裂纹缺陷检测,为管道全向裂纹缺陷检测提供参考。

In order to realize the detection of the crack defects with different directions in the pipeline effectively using electromagnetic ultrasonic guided wave,the mechanism of spiral propagation of ultrasonic guided wave was studied,and an electromagnetic ultrasonic spiral guided wave transducer used for the detection of the oblique crack defects in pipeline was designed.Based on the Biosvall's law, the mathematical model of the equivalent closed coil of the spiral guided wave transducer was established.The relationship between the magnetic induction intensity of electromagnetic ultrasonic spiral guided wave transducer and the propagation direction of spiral guided wave main ultrasonic beam was derived and analyzed.Experiments verify the propagation mechanism and corresponding crack defect detection capability of the spiral guided wave with different angles of the spiral guided coil.Results show that the propagation direction of the main ultrasonic beam of the electromagnetic ultrasonic spiral guided wave is perpendicular to the working wire of the coil.Changing the spiral angle of the transducer coil can control the propagation direction of the electromagnetic ultrasonic.guided wave in pipeline.The transducers with different coil spiral angles can realize the defect detection of the cracks in different oblique angles in pipeline,which provides a reference for the detection of omnidirectional crack defects in pipeline.