基于超声波的结构内部温度场重建方法研究

Reconstruction of Internal Temperature Distribution in Solid Structure by Ultrasound Thermometry

针对在工业应用中对结构内部温度场无损测量的需求,以超声测温机理和热传导理论为基础,提出一种一维稳态结构内部温度场的重建方法,并且设计一套微秒级超声声时测量的超声测温系统以验证此方法的可行性。根据所提出的结构内部温度场重建方法,分别进行超声声速与温度的标定试验和结构内部一维稳态非均匀温度场的重建试验,测量了结构试样在单边受热过程中的超声声时,构建了结构试样底面在100℃、150℃、200℃加热,上表面15℃水冷情况下的内部温度场分布,并且系统分析冷端边界条件、标定方程、热扩散系数、热膨胀等因素对重建效果的影响。结果表明:本方法能够实现结构内部一维稳态温度场的重建,并且在对于温度梯度明显的区域具有较好的重建精度。

To satisfy the requirements of the industrial application for the non-destructive measurement of internal temperature in structures, a new method for reconstructing the one-dimensional steady internal temperature distribution in solid structures using ultrasound thermometry mechanism and heat conduction theory is presented. And an ultrasonic system of microsecond measurement is designed to verify the feasibility of the method. According to the proposed temperature field reconstruction method, the calibration experiments of the ultrasonic velocity and temperature and the one-dimensional steady non-uniform temperature field reconstruction experiments in the structures are carried out. Ultrasonic pulse echo measurements are performed for the aluminum cylinder of 200 mm thickness, whose bottom side is heated by a heater of 100 ℃, 150 ℃ and 200 ℃, and simultaneously the top surface is cooled down by the 15 ℃ water to reconstruct the internal temperature field distribution. Besides, the influences of the cold boundary condition, the calibration equation, thermal diffusion coefficient, and thermal expansion on the precision of reconstruction are carried out in detail. It shows that the presented method can realize the reconstruction of the internal one dimensional steady temperature field in structures, and has better reconstruction precision for the regions with obvious temperature gradients.