疏水表面减阻环带实验研究

针对疏水功能材料在流动减阻方面的应用, 选取典型不同粗糙度、不同疏水性的功能涂层表面, 通过新型环带实验研究了其阻力特性, 并获得了相应的扭矩和减阻率曲线. 实验采用测量圆盘带动环带旋转时的扭矩的方法间接计算环带表面所受的摩阻, 突破了传统微管道实验在尺度上的限制, 避免了水洞实验中影响因素过多的弊端, 对疏水材料的宏观应用有着重要意义. 实验证实了在宏观尺度下疏水涂层在低雷诺数时的减阻作用; 但在高雷诺数时, 减阻作用减弱, 甚至部分涂层有增阻作用, 而压差阻力的迅速增大是造成增阻的主要原因. 通过对比分析认为: 低雷诺数时, 疏水特性对于减阻效果影响更大; 而高雷诺数时, 粗糙度起更大作用, 甚至可能起到增阻的反效果. 关键词： 疏水表面 环带实验 粗糙度 减阻

Investigation about drag reduction annulus experiment of hydrophobic surface

For the drag reduction application of hydrophobic material, the drag characteristic of typical surface with different roughness or different hydrophobicity is studied by a new annulus experiment. The corresponding torque characteristic and drag reduction rate curve are acquired. The experiment indirectly calculate the surface friction of the annulus by measuring the torque of disk driving annulus and breaks through the limitation of scale in traditional microchannel experiment, avoids the drawbacks of too many influencing factors in water-tunnel experiment, and has important significance in macro application of hydrophobic material. The drag reduction effect of hydrophobic surface is proved at low Reynolds number in macroscale; however, at high Reynolds number, it will be weakened or even changed to drag producing effect, and the rapid increase of pressure drag is the major reason for increasing resistance. Through comparative analysis we find that at low Reynolds number, there will be greater effect of hydrophobicity for drag reduction; where as at high Reynolds number, the roughness will play a greater role, and may even be counterproductive to the increasing resistance.
Keywords： hydrophobic surface annulus experiment roughness drag reduction