布朗运动和湍流扩散作用下槽流中纤维悬浮流动特性的研究
发布时间：2019-07-02 15:56
【摘要】：为了探讨槽道中纤维悬浮湍流场特性,本文对修正的雷诺平均纳维-斯托克斯方程、含纤维项的湍动能和耗散率方程、纤维动力学方程以及纤维取向概率密度函数方程进行了数值研究,同时进行了相关实验以验证计算结果.研究结果表明,流场中尤其是近壁区域,纤维取向趋向于与流动方向一致,且该现象随着雷诺数和纤维浓度的减小以及纤维长径比的增大而更为明显.纤维在槽道中分布不均匀,但随着雷诺数的增大和纤维长径比的减小趋于均匀.相对于单相流,纤维悬浮流的流向平均速度剖面更陡峭,且剖面斜率随着纤维浓度、长径比的增大以及雷诺数的减小而变大,纤维的存在使湍流场的湍动能和雷诺应力减小,且减小程度随着纤维浓度和长径比的增大以及雷诺数的减小而增加.流场中的第一法向应力差小于0.05且远小于剪切应力.从壁面到中心,剪切应力增加而第一法向应力差减小.剪切应力和第一法向应力差都随着纤维浓度和长径比的增大而增大.随着雷诺数的增大,剪切应力增大而第一法向应力差减小.纤维浓度对于剪切应力和第一法向应力差的影响比纤维长径比更显著.
[Abstract]:In order to investigate the characteristics of fiber suspension turbulent field in the channel, the modified Reynolds average Neville-Stokes equation, the turbulent kinetic energy and dissipation rate equation with fiber term, the fiber dynamics equation and the fiber orientation probability density function equation are studied numerical. At the same time, the related experiments are carried out to verify the calculated results. The results show that the fiber orientation tends to be consistent with the flow direction in the flow field, especially in the near-wall region, and the phenomenon is more obvious with the decrease of Reynolds number and fiber concentration and the increase of fiber aspect ratio. The fiber distribution in the channel is not uniform, but with the increase of Reynolds number and the decrease of fiber aspect ratio, it tends to be uniform. Compared with single-phase flow, the average velocity profile of fiber suspension flow is steeper, and the slope of the section increases with the increase of fiber concentration, aspect ratio and Reynolds number. The turbulent kinetic energy and Reynolds stress of turbulent flow field decrease with the presence of fiber, and the degree of decrease increases with the increase of fiber concentration and aspect ratio and the decrease of Reynolds number. The first normal stress difference in the flow field is less than 0.05 and much smaller than the shear stress. From the wall to the center, the shear stress increases and the first normal stress difference decreases. The shear stress and the first normal stress difference increase with the increase of fiber concentration and aspect ratio. With the increase of Reynolds number, the shear stress increases and the first normal stress difference decreases. The effect of fiber concentration on shear stress and first normal stress difference is more significant than that of fiber aspect ratio.
【作者单位】： 浙江大学航空航天学院力学系;
【基金】：国家自然科学基金重大项目(批准号:11132008)资助的课题~~
【分类号】：O357.5
本文编号：2509065
[Abstract]:In order to investigate the characteristics of fiber suspension turbulent field in the channel, the modified Reynolds average Neville-Stokes equation, the turbulent kinetic energy and dissipation rate equation with fiber term, the fiber dynamics equation and the fiber orientation probability density function equation are studied numerical. At the same time, the related experiments are carried out to verify the calculated results. The results show that the fiber orientation tends to be consistent with the flow direction in the flow field, especially in the near-wall region, and the phenomenon is more obvious with the decrease of Reynolds number and fiber concentration and the increase of fiber aspect ratio. The fiber distribution in the channel is not uniform, but with the increase of Reynolds number and the decrease of fiber aspect ratio, it tends to be uniform. Compared with single-phase flow, the average velocity profile of fiber suspension flow is steeper, and the slope of the section increases with the increase of fiber concentration, aspect ratio and Reynolds number. The turbulent kinetic energy and Reynolds stress of turbulent flow field decrease with the presence of fiber, and the degree of decrease increases with the increase of fiber concentration and aspect ratio and the decrease of Reynolds number. The first normal stress difference in the flow field is less than 0.05 and much smaller than the shear stress. From the wall to the center, the shear stress increases and the first normal stress difference decreases. The shear stress and the first normal stress difference increase with the increase of fiber concentration and aspect ratio. With the increase of Reynolds number, the shear stress increases and the first normal stress difference decreases. The effect of fiber concentration on shear stress and first normal stress difference is more significant than that of fiber aspect ratio.
【作者单位】： 浙江大学航空航天学院力学系;
【基金】：国家自然科学基金重大项目(批准号:11132008)资助的课题~~
【分类号】：O357.5
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