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The blocking effect of the sand fences quantified using wind tunnel simulations 被引量:5
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作者 YU Yan-ping ZHANG Ke-cun +2 位作者 AN Zhi-shan WANG Tao HU Fei 《Journal of Mountain Science》 SCIE CSCD 2020年第10期2485-2496,共12页
Fences are one of the most effective measures to prevent and control wind-blown sand disasters,and the blocking effect of fences is largely determined by their porosity and height(H).This study employed wind tunnel ex... Fences are one of the most effective measures to prevent and control wind-blown sand disasters,and the blocking effect of fences is largely determined by their porosity and height(H).This study employed wind tunnel experiments to measure wind velocities on both sides of wire mesh sand fences with porosities of 75%,63%,56%,36%and heights of 10,5 and 2 cm.The effects of porosity and height on the blocking effect of the fences were evaluated on the basis of velocity variability,flow field,and the wind velocity reduction coefficient.Results show that the smaller the porosity,the stronger the blocking effect.The fence with a porosity of 36%had the strongest windproof efficiency of 0.70 and longest protection range of 9 H,and thus showed the best applicability in preventing and controlling wind-blown sand disasters.The fence with a porosity of 56%showed a windproof efficiency of 0.31 and a protection range of 7 H,which could be considered for adoption.However,fences with porosities of 75%and 63%were not recommended to be adopted,because their windproof efficiency and protection range were very small.Overall,the higher the fence,the stronger the blocking effect.The highest fence(10 cm)had the longest protection range of 90 cm,which was the best in application.Nevertheless,the 5 and 2 cm fences were almost consistent with 10 cm fence in windproof efficiency,which was still suitable for wind and sand fixation. 展开更多
关键词 porous fence fence height Windproof efficiency Protection range Blocking effect
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Wind tunnel test on the effect of metal net fences on sand flux in a Gobi Desert, China 被引量:20
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作者 WANG Tao QU Jianjun +2 位作者 LING Yuquan XIE Shengbo XIAO Jianhua 《Journal of Arid Land》 SCIE CSCD 2017年第6期888-899,共12页
The Lanzhou-Xinjiang High-speed Railway runs through an expansive windy area in a Gobi Desert, and sand-blocking fences were built to protect the railway from destruction by wind-blown sand. However, the shielding eff... The Lanzhou-Xinjiang High-speed Railway runs through an expansive windy area in a Gobi Desert, and sand-blocking fences were built to protect the railway from destruction by wind-blown sand. However, the shielding effect of the sand-blocking fence is below the expectation. In this study, effects of metal net fences with porosities of 0.5 and 0.7 were tested in a wind tunnel to determine the effectiveness of the employed two kinds of fences in reducing wind velocity and restraining wind-blown sand. Specifically, the horizontal wind velocities and sediment flux densities above the gravel surface were measured under different free-stream wind velocities for the following conditions: no fence at all, single fence with a porosity of 0.5, single fence with a porosity of 0.7, double fences with a porosity of 0.5, and double fences with a porosity of 0.7. Experimental results showed that the horizontal wind velocity was more significantly decreased by the fence with a porosity of 0.5, especially for the double fences. The horizontal wind velocity decreased approximately 65% at a distance of 3.25 m(i.e., 13 H, where H denotes the fence height) downwind the double fences, and no reverse flow or vortex was observed on the leeward side. The sediment flux density decreased exponentially with height above the gravel surface downwind in all tested fences. The reduction percentage of total sediment flux density was higher for the fence with a porosity of 0.5 than for the fence with a porosity of 0.7, especially for the double fences. Furthermore, the decreasing percentage of total sediment flux density decreased with increasing free-stream wind velocity. The results suggest that compared with metal net fence with a porosity of 0.7, the metal net fence with a porosity of 0.5 is more effective for controlling wind-blown sand in the expansive windy area where the Lanzhou-Xinjiang High-speed Railway runs through. 展开更多
关键词 wind-blown sand wind tunnel experiment porous fence flow field sediment flux density Lanzhou-Xinjiang High-speed Railway Gobi Desert
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Experimental and numerical study of fence effects on dust emission into atmosphere from open storage piles 被引量:1
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作者 S.TORNO J.TORA-O +2 位作者 M MENéNDEZ M.GENT I.áLVAREZ 《Journal of Central South University》 SCIE EI CAS 2011年第2期411-419,共9页
The results obtained from the research on the behaviour of fences (solid and porous) in the protection against particulated material emission to the atmosphere from open storage piles,are presented. This research was ... The results obtained from the research on the behaviour of fences (solid and porous) in the protection against particulated material emission to the atmosphere from open storage piles,are presented. This research was carried out through computational fluid dynamics (CFD) simulation by software Ansys CFX-10.0 in 3D,with K-epsilon being considered in the turbulence model. The efficiency of the use of porous fences as a protection against the wind flow,which interacts with an open storage pile,is shown. The use of these fences (when porosity is ε=30%) allows the reduction of wind flow velocity which interacts with the pile in comparison with the case of no use of fences (when porosity is 100%). In addition,the use of porous fences makes the velocity vortex,which is formed between the solid fence (ε=0%) and the pile,disappear,reducing the particle emission to the atmosphere by 78%. 展开更多
关键词 open storage pile air pollution particle emission wind erosion porous fence computational fluid dynamics
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ZnCl2 salt facilitated preparation of FeNC: Enhancing the content of active species and their exposure for highly-efficient oxygen reduction reaction 被引量:7
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作者 Zhan Xin Mao Min Jie Wang +5 位作者 Lu Liu Lishan Peng Siguo Chen Li Li Jing Li Zidong Wei 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2020年第5期799-806,共8页
Introducing catalytically-active Fe and N into carbon materials results in promising FeNC catalysts for oxygen reduction reaction. However, the doped Fe and N species are frequently subject to heavy loss in a traditio... Introducing catalytically-active Fe and N into carbon materials results in promising FeNC catalysts for oxygen reduction reaction. However, the doped Fe and N species are frequently subject to heavy loss in a traditional carbonization process owing to Fe agglomeration and evaporation of N-contained small molecules. Besides, pyrolysis may make materials sintering which embeds a large number of active sites in the bulk phase and impedes direct exposure of reactive centers to the reactants. We here report that when calcinations, the addition of ZnCl2, an ordinary salt with very wide melting temperature range well covering the carbonization process of the precursor iron porphyrin, can significantly enhance the doping level of the active species and simultaneously create highly porous structures for FeNC catalysts. The obtained FeNC demonstrates ultrahigh catalytic activities even significantly better than Pt/C in oxygen reduction reaction. 展开更多
关键词 fenc Catalyst ZNCL2 porous carbon Oxygen reduction reaction Fuel cell
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