Finite Element Analysis and Experiments on Mechanism of Wear inside Pipe

本研究旨在阐明弯管附近冲蚀磨损的机理。在2005财年，我们对管道内的流动进行了有限元模拟，并对管道内的流场进行了研究。选取了几个弯道的管道作为模拟对象。管子和弯管的名义直径为80 mm，弯曲曲率分别为76 mm、114 mm和342 mm，流速范围为lm/S到5m/S。作为这些模拟的结果，我们指定了流场，并确定了高压区和高速区。2006财年，我们进行了一次实验，以明确磨损的位置。在实验中，我们将沙粒混合在水中，并观察到管道内附着的胶带上的划痕。对比有限元模拟和实验，发现磨损发生在曲线外的高压区，而磨损发生在曲线内的高速区。在高压区，水流冲击并侵蚀管壁。平均流量是加速磨损的重要因素。我们还发现，在两个弯头之间插入短的直管有效地减少了磨损

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