Finite Element Analysis and Experiments on Mechanism of Wear inside Pipe

本研究的目的是阐明弯管附近侵蚀引起管道磨损的机理，2005财年，我们采用有限元方法模拟了管道内的流动，研究了管道内的流场。选择具有少量弯曲的管道作为模拟的目标。管道和弯曲的公称直径为80 mm，弯曲曲率为76 mm、114 mm和342 mm，流速范围为1 m/s ~ 5 m/s。根据模拟结果，确定了流场，确定了高压区和高速区。2006年度，为了明确磨损部位，进行了实验。在实验中，我们将沙粒混合在水中，并观察了管道内部胶带上的划痕。通过有限元模拟和实验对比发现，磨损主要发生在曲线外侧的高压区，而曲线内侧的高速区磨损较小。在高压区，流体冲击并侵蚀管壁。平均流量是加速磨损的重要因素。我们还发现在两个弯管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