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管道的弯管段、闸阀等处常常面临含砂流动的冲蚀磨损而导致管壁减薄或泄漏。为研究弯管段冲蚀磨损的主要机制,进行了加入5%石英砂的固液两相管流循环试验。试验按砂粒粒径分组,主要观测布置在弯管段的一组碳钢贴片在2~3小时后的壁面冲蚀特征。用失重法计算各贴片的冲蚀速率,基于扫描电镜(SEM)研究了贴片表面的损伤形貌。冲蚀后的贴片表面既有犁沟、挤压凹坑及划痕,亦有圆形蚀坑。能谱分析(EDS)显示有一定量的铁氧化物,且不同位置处的贴片失重率有正有负,由此可见导致贴片表面破坏的机制既包括切削、挤压和二次冲击等含沙流流动的机械作用,也伴随着腐蚀作用。这两种机制在弯管各区有不同的体现,且受砂粒粒径的影响。用数值模拟的两相流冲蚀弯管段流场压力和颗粒分布特征做了验证。结果表明弯管段的壁面损伤机制在外拱壁面以颗粒冲击和切削为主,在内拱璧面则以氧化腐蚀为主。
Elbow pipe sections, gate valves, etc. are often faced erosion of sand flow erosion led to thinning or leakage of the wall. In order to study the main mechanism of erosion and erosion of elbow section, a circulation test of solid-liquid two-phase pipe flow with 5% quartz sand was carried out. The test is grouped according to the grain size of the sand. The wall erosion characteristics of a group of carbon steel patches arranged in the bend section after 2 to 3 hours are mainly observed. The erosion rate of each patch was calculated by weight loss method. The damage morphology of patch surface was studied based on scanning electron microscope (SEM). Erosion after the patch surface both furrows, squeezing pits and scratches, there are circular pits. Energy dispersive spectroscopy (EDS) showed that there was a certain amount of iron oxide, and the weight loss rate of the patch at different positions had positive and negative. Thus, the mechanism of surface damage caused by the patch included both cutting, squeezing and secondary impact The mechanical action of sand flow is also accompanied by corrosion. These two mechanisms have different manifestations in the bending zone, and are affected by the grain size of the sand. The flow field pressure and particle distribution characteristics of the two-phase flow eroded elbow section were numerically simulated. The results show that the wall damage mechanism of the elbow section is mainly particle impact and cutting on the outer arch wall, and the oxidation and corrosion are mainly on the inner arch face.