基于SH模态导波杆的电站高温结构壁厚测量方法

Thickness Measuring Method of High-temperature Power Plant Structures Based on SH Mode Waveguide

提出了一种基于SH模态导波杆的电站高温结构壁厚测量方法,该方法使用导波杆将压电传感器与高温被测结构隔开。通过研究发现非频散SH模态导波能通过矩形横截面导波杆将导波信号由传感器导入到高温被测结构中。实验验证了通过特定夹具以干耦合方式将导波杆固定在被测结构表面可以获得较好的信号。使用2MHz中心频率下的汉宁窗调制正弦波信号实现了对处于不同温度被测结构壁厚的监测,室温(25℃)时,壁厚测量值与实际厚度相差0.016mm,高温被测结构实验信号也非常好,波速测量值与拟合曲线所得速度值误差范围为0.1%~2.5%。

It is significant to put forward a thickness measuring method ot high temperature power plant structures based on SH mode, which used a waveguide to isolate the transducers from the high- temperature measurement zones. It was found that a nondispersive SH mode guided wave in rectangu- lar waveguide was employed to transmit the guided wave signals from the transducers to the measure- ment zones. In addition, experiments were investigated by dry-coupled to attach the waveguides to the components, whichshows that clamping the waveguides to the component surfaces may get best re- sults. By using Hanning window modulated sine wave signals with 2 MHz center frequency, the thick- ness difference of the measured values and actual values of wall thickness is 0.016 mm at the room temperature（25℃）. Performance at high temperatures was tested without signal degradation. The er- ror ranges of wave velocity measurement values and the velocities of the fitting curve are 0.1% to 2.5%.