Reconstruction of Internal Temperature Distribution in Solid Structure by Ultrasound Thermometry

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 200mm 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.