一种考虑声线弯曲的温度场重建算法

声波在非均匀温度场中传播时会由于声波的折射而产生声线弯曲现象。为提高非均匀温度场声学CT (Computer Tomography)重建精度,提出一种考虑声线弯曲的重建算法。首先用最小二乘法获得一个不考虑声线弯曲的重建温度场,然后用打靶-插值法确定本征声线出射角,用三角形前向展开法追踪声线,获得此温度场中声波发射/接收器间的本征声线,建立本征声线上声波传播时间与温度分布间的关系,进而实现考虑声线弯曲的最小二乘法温度场重建。单峰、双峰温度场仿真重建结果表明:所采用的本征声线追踪法计算简单运行速度快;考虑声线弯曲后,可明显提高温度场重建精度。因此所提重建算法能更好地适应实际温度场重建需求。

A reconstruction algorithm of temperature field taking into account the bending of sound wave paths

When a sound wave passes through a non-uniform temperature field,the sound wave path will bend due to refraction.In order to improve the reconstruction accuracy of un-uniform temperature fields by acoustic Computer Tomography,a reconstruction algorithm considering the bending of sound wave paths is proposed.First,obtain a reconstruction temperature field by the least-squares method without considering the bending of sound wave paths.Second,find the eigenrays between the sound transmitters/receivers in the reconstruction field by using the triangular forward deployment method for sound ray tracing and shooting-interpolation method for evaluating the emergent angle of eigenrays.Third,establish the relationship between the acoustic travel-times over the eigenrays and the temperature distribution.Last,reaHze the reconstruction of temperature field by the least-squares method with considering the bending of sound wave paths.The reconstruction results of single-peak and double-peak model temperature fields show that the method used for finding eigenrays is simple in calculation and fast in execution;the reconstruction accuracy can be improved obviously by considering the bending of sound wave paths.Thus the reconstruction algorithm proposed is more appropriate for reconstruction of actual temperature fields.