摘要
孔隙率是影响抑尘网防护效果的最主要因素,不同孔隙率抑尘网对料堆表面的显著作用区域不同,高孔隙率(ε≥0.3)网后料堆中下部扬尘得到明显抑制,低孔隙率(ε<0.3)网的抑尘作用则于料堆上部突显.基于均匀孔隙率的抑尘区域提出不同孔隙率组合的非均匀抑尘网,选取6种典型非均匀工况,应用Fluent6.3对网和料堆周围流场进行数值模拟,结果显示:网下部孔隙率(εL)相同,上部孔隙率(εH)由0增至0.1时,网后气流扰动减弱,基于湍流结构和料堆受力判定εH取0.1较好;网上部孔隙率(εH)相同,下部孔隙率(εL)由0.3增至0.6时,紧贴料堆表面风速随εL增大而增大,εL为0.3时最优.比较非均匀抑尘网最佳工况(εH=0.1/εL=0.3)与均匀网(ε=0.1和ε=0.3)的料堆表面受力显示:εH=0.1/εL=0.3非均匀网可使起尘量最大的迎风面的各个区域剪切力均显著减小,中下部比ε=0.1时减小85.2%,上部比ε=0.3时减小84.3%,料堆表面剪切力总和的减少量可达均匀网时的50%左右.
Porosity is the most important parameter affecting the efficient of fences, however, the distinct shelter regions varied with different porosity. At high porosities （ε≥0.3）, the dust emission in the middle and lower parts of the pile over the fence decreased significantly, while the shelter mainly reflected in the upper part at low porosities （ε＆lt;0.3）. Obtaining effective protection on each site, this research introduced, based on the reduction region of the uniform porosity, a new combination of non-uniform fence with different porosities for the upper and lower halves. The flow flied behind a porous fence was numerically simulated by software Fluent6.3with six typical combinations of the non-uniform fence. Results showed that when the lower fence porosity of the fence （εL） kept consistent and the upper fence porosity （εH） transformed from 0to 0.1, the airflow turbulence weakened distinctly. Considering turbulence structure and stress of the pile, the fence with the upper porosityεH= 0.1was more accepted. Meanwhile, when the upper porosity （εH） remained identical, and the lower porosity （εL） increased from 0.3to 0.6,the speed of attached flow along the surface increased with the increasing porosity, therefore, the optimum porosity of the lower half fence （εL） was set to 0.3. The shelter effect of non-uniform fence was estimated by comparing the preferred combination （εH=0.1/εL=0.3）with uniform fence porosityε=0.1 andε=0.3. The analysis indicated the non-uniform porous fence （εH=0.1/εL=0.3） seemed to be the most effective in abating the dust emission, especially in reducing the shear stress of the windward which aroused the maximum dust emission. The shear stress of the non-uniform porous fence, in the middle and lower part, decreased by 85.2% for the uniform fence with porosityε=0.1, and 84.3% in the upper part for the fence with the porosityε=0.3, respectively. Besides, the non-uniform porous fence （εH=0.1/εL =0.3） could reduce the surface shear fo
出处
《中国环境科学》
EI
CAS
CSCD
北大核心
2016年第6期1697-1704,共8页
China Environmental Science
基金
国家自然科学基金资助项目(51108295)
关键词
防风抑尘网
非均匀孔隙率
数值模拟
剪切力
porous fence
non-uniform porosity
numerical simulation
shear stress
