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Study on Frictional Resistance of Drag Reducing Solid Wall

减阻实体墙摩擦阻力研究

基本信息

批准号：
15360099
负责人：
MIZUNUMA Hiroshi
金额：
$ 9.66万
依托单位：
Tokyo Metropolitan University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-15360099/
关键词：
Fluid mechanics Newtonina fluid Drag reduction Flow in a Duct Flow past a sphere Hydrophobic Surface Disk with Fine Grooves Shear-Force Pump 撥水性壁面矩形管内流れ球周りの流れ回転円板周りの流れ滑りの境界条件疎水性壁面

项目摘要

In this study, we studied on the flow characteristics of a tap water or glycerin solutions for the flow in a duct, the flow past a sphere, and the flow in an enclosed rotating disk with a drag reducing surface.For a flow in a duct with hydrophobic coating surface, it was clarified that the laminar drag reduction occurred in the Reynolds number range of 150 <Re < 770. The maximum drag reduction ratio is 12.6% at Re = 649.For the flow past a sphere, it was clarified that the vortex street was not found at the Re < 320 in the hydrophobic wall and the separation point moved downstream compared with that of a conventional smooth wall. The drag reduction occurred in the flow and the maximum drag reduction ratio was 14.6% at the Re=93.2. In this simulation, the method for tracking gas-liquid interfaces has been used the VOF technique, and the method for modeling surface tension effects on fluid motion has been used the CSF model. The flow patterns for the numerical simulation results agreed with that of the flow visualization results.For the flows around an enclosed rotating disk with the fine spiral grooves, it was seen that the drag reduction occurs in the turbulent flow range at the non-dimensional axial clearance (s/a) = 0.011, 0.22 and 0.33, the maximum drag reduction ratio is approximately 15%. The fine spiral groove has the effect which suppresses the development of the fluctuation of transition region, and which delays the generation of the local turbulence in the transition range.

研究了自来水和甘油溶液在管道、球体和带有减阻表面的封闭旋转圆盘中的流动特性，发现在带有疏水涂层的管道中，雷诺数Re = 150 <Re < 770时，均发生层流减阻.当Re = 649时，减阻率最大为12.6%。对于圆球绕流，当Re < 320时，疏水壁面没有出现涡街，分离点比光滑壁面向下游移动。在Re=93.2时，流动阻力降低，最大减阻率为14.6%。在本模拟中，追踪气液界面的方法采用VOF技术，模拟表面张力对流体运动影响的方法采用CSF模型。数值模拟结果的流动形态与流动可视化结果一致，对于带有细螺旋槽的封闭旋转圆盘的绕流，可以看出，在无因次轴向间隙（s/a）= 0.011，0.22和0.33时，在湍流范围内发生了减阻，最大减阻率约为15%。细螺旋槽的存在抑制了转捩区脉动的发展，延缓了转捩区局部湍流的产生。