This paper focuses on evaluation of differences in the newly manufactured U-tubes and ones after operation. Differences in geometry and internal surface roughness were investigated and a flow simulation was carried out in the Ansys Fluent software, where properties such as flow nature, maximum velocity and pressure drop were examined. A numerical model validation process was carried out with an application of PIV experiments. The digital models of the U-tube were obtained with an application of computer tomography. As a result of the tests, it has been noticed that the U-tube after operation has a much more distorted cross-sectional shape comparing to the shape of the new one. Moreover, the U-tube after operation is characterized by a 3-fold higher average surface roughness Sa value than one obtained in the new tube. The maximum flow velocities for the tube after operation are about 3.4% higher than ones reached for theoretical tube.

本文着重于评估新制造的U型管和术后U型管的差异。研究了几何形状和内部表面粗糙度的差异，并在Ansys Fluent软件中进行了流动模拟，在该软件中检查了诸如流动性质，最大速度和压降之类的属性。应用PIV实验进行了数值模型验证过程。U形管的数字模型是通过计算机断层扫描技术获得的。作为测试的结果，已经注意到，与新的U形管的形状相比，操作后的U形管的横截面形状失真得多。此外，U形管在操作后的特征是平均表面粗糙度Sa高3倍值比新管中获得的值高。试管的最大流速比理论试管达到的流速高约3.4％。