充分发展湍流管道内壁边界的红外定量识别

Infrared quantitative identification for inner boundary of fully developed turbulent pipeline

基于导热的管道内壁边界识别已发展成熟,但更贴合实际的湍流管道内壁边界的定量识别尚未见报道。通过关联COMSOL和MATLAB,利用有限元方法和Levenberg-Marquardt算法对二维轴对称充分发展的湍流管道内壁边界形状的稳态识别进行研究。数值实验证明了本方法的有效性。结果表明,在含内壁缺陷的湍流管道中,外壁最大温差和由缺陷引起的绝对温差并不是同步增加的;在进行内壁边界反问题识别时,由于绝对温差中负增长的出现,绝对温差越大,识别结果未必越好;识别精度在不规则内壁终点处略微变差。

Although the identification of pipelines′inner boundary based on heat conduction has been matured,the quantitative identification of inner boundary of turbulent pipe,which is more practical,has scarcely been reported yet.The steady-state identification of the inner boundary shape of a turbulent pipe with fully developed two-dimensional axial symmetry was studied through the connection of COMSOL and MATLAB,as well as the use of finite element method and Levenberg-Marquardt method.The validity of this method was proved by numerical experiments.The results show that,in a turbulent pipeline with a defective inner boundary,the maximum temperature difference of outer wall and the absolute temperature difference caused by defect do not increase synchronously.During the identification of inverse inner boundary problem,due to the negative growth in the absolute temperature difference,the identification results do not necessarily improve with the increase of absolute temperature difference.The identification accuracy slightly deteriorates at the end of the irregular inner boundary.