Finite Element Analysis and Experiments on Mechanism of Wear inside Pipe

本研究的目的在于阐明弯道附近冲蚀引起管道磨损的机理。2005会计年度，采用有限元法对管道内流动进行了模拟，研究了管道内的流场。选择弯道较少的管道作为模拟对象。管道和弯头公称直径为80mm，弯头曲率为76mm、114mm和342mm，流速范围为lm/s至5m/s。根据这些模拟结果，我们指定了流场，并确定了高压区和高速区。在2006财政年度，我们进行了一项实验，以明确磨损的位置。在实验中，我们将砂粒掺入水中，观察到粘在管道内部的胶带上有划痕。有限元模拟与实验对比发现，曲线外高压区出现磨损，曲线内高速区磨损较少。在高压区，流体冲击并侵蚀管壁。发现平均流量是加速磨损的重要因素。我们还发现，在两个弯头之间插入短直管可以有效地减少磨损

The purpose of this research is to clarify the mechanism of wear of pipe caused by erosion near bends.In fiscal year 2005, we simulated flows in pipeline by FEM and studied the flow field inside the pipe. Pipelines with a few bends were chosen as target of simulations. Nominal diameter of the pipe and bend is 80mm, bend curvatures are 76mm, 114mm and 342mm and flow velocity ranges from lm/s to 5m/s. As the result of these simulations, we specified the flow field and located high pressure zones and high speed zones.In fiscal year 2006, we conducted an experiment to clarify the location of wear. In the experiment, we mixed sand particles in water and observed scratches on tapes attached inside of the pipe. Comparing the FEM simulations and experiments, we found that the wear occurs at high pressure zone outside of the curve whereas less wear occurs at the high speed zone inside of the curve. At the high pressure zone, the flow hit and erode the pipe wall. Mean flow rate is found to be important factor which accelerate the wear. We also found insertion of short straight pipe between two bends effectively reduces wear