高温结构内部温度场和厚度的超声同步测量方法研究

Research on Ultrasonic Synchronous Measurement of Temperature Field and Thickness in High-temperature Structure

高温结构内部温度及其厚度的预测在航空航天、石油化工等领域具有十分重要的作用和意义,譬如高温管道由于流体长时间冲刷带来的管壁减薄等问题需要对管壁结构内部温度和厚度变化进行同时在线监测。首先建立了基于超声脉冲回波法的同时测温测厚理论模型,根据热-声-固耦合理论,采用共轭梯度法反演热流和最速下降法反演厚度相结合的交替迭代辨识方法实现瞬态传热条件下固体结构内部温度场和厚度的同步测量。另外,基于20钢的瞬态传热试验,对交替迭代反演方法的有效性和准确性进行试验验证和分析,并系统分析了物性参数、采样点数、边界温度和声时精度对重建方法的影响。研究结果表明,基于超声渡越声时的交替迭代方法反演得到的结构厚度符合物理实际,重建得到的结构内部瞬态温度分布精度较高且实时性好,有利于促进高温环境下超声同步测温测厚技术的发展,具有重要的工程应用价值。

The prediction of the internal temperature and thickness of the high-temperature structure has a very important role and significance in the fields of aerospace and petrochemical industry,such as the thinning of the pipe wall caused by the long-term erosion of the fluid in the high-temperature pipeline,which requires simultaneous online monitoring of the internal temperature and thickness change of the pipe wall structure.Firstly,a theoretical model based on ultrasonic pulse-echo method for simultaneous measurement of temperature and thickness is established.According to thermo-acoustic-solid coupling theory,an alternate iterative identification method combining conjugate gradient method for heat flow inversion and the steepest descent method for thickness inversion is used to realize the simultaneous measurement of temperature field and thickness in solid structure under transient heat transfer condition.In addition,based on the transient heat transfer test of 20#steel,the validity and accuracy of the alternate iterative inversion method are verified and analyzed,and the influence of physical property parameters,sampling points,boundary temperature and time accuracy on the reconstruction method are systematically analyzed.The results show that the structure thickness obtained by the alternate iteration method based on ultrasonic transit sound is consistent with the physical reality,and the reconstructed transient temperature distribution inside the structure has high accuracy and good real-time performance,which is beneficial to promote the development of ultrasonic simultaneous temperature measurement and thickness measurement technology under high temperature environment,and has important engineering application value.