It is well known that shark skin surface can effectively inhabit the occurrence of turbulence and reduce the wall friction, but in order to understand the mechanism of drag reduction, one has to solve the problem of t...It is well known that shark skin surface can effectively inhabit the occurrence of turbulence and reduce the wall friction, but in order to understand the mechanism of drag reduction, one has to solve the problem of the turbulent flow on grooved-scale surface, and in that respect, the direct numerical simulation is an important tool. In this article, based on the real biological shark skin, the model of real shark skin is built through high-accurate scanning and data processing. The turbulent flow on a real shark skin is comprehensively simulated, and based on the simulation, the drag reduction mechanism is discussed. In addition, in order to validate the drag-reducing effect of shark skin surface, actual experiments were carried out in water tunnel, and the experimental results are approximately consistent with the numerical simulation.展开更多
将采用分散聚合法制备的水包水乳液减阻剂直接溶解于纯水中,配制成滑溜水;通过环境扫描电子显微镜与室内管道摩阻仪对减阻剂进行微观结构表征与减阻性能测试。实验结果表明,该减阻剂具有良好的速溶性,能在 98 s 内溶解完全;减阻剂浓度...将采用分散聚合法制备的水包水乳液减阻剂直接溶解于纯水中,配制成滑溜水;通过环境扫描电子显微镜与室内管道摩阻仪对减阻剂进行微观结构表征与减阻性能测试。实验结果表明,该减阻剂具有良好的速溶性,能在 98 s 内溶解完全;减阻剂浓度和高价离子浓度影响滑溜水的减阻性能,其中,Ca^2+,Fe^3+,SO4^2-质量浓度分别超过 75,20,100 g/L 时,才会影响减阻效率;在滑溜水实际应用时应侧重非结构黏度的减阻作用。展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No. 50775006)the National High Technology Research and Development Program of China (863 Program, Grant No. 2009AA043802)
文摘It is well known that shark skin surface can effectively inhabit the occurrence of turbulence and reduce the wall friction, but in order to understand the mechanism of drag reduction, one has to solve the problem of the turbulent flow on grooved-scale surface, and in that respect, the direct numerical simulation is an important tool. In this article, based on the real biological shark skin, the model of real shark skin is built through high-accurate scanning and data processing. The turbulent flow on a real shark skin is comprehensively simulated, and based on the simulation, the drag reduction mechanism is discussed. In addition, in order to validate the drag-reducing effect of shark skin surface, actual experiments were carried out in water tunnel, and the experimental results are approximately consistent with the numerical simulation.
