Aerodynamic Evaluation of the Optimal Porosity of Sand Fences
Updatetime：2011-02-11From：
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In order to study the dynamical mechanism of sand fences´sheltering effect, the optimal porosity of fences was discussed and evaluated from aerodynamic angle and based on the measured velocity data by PIV technology in the wind tunnel. Although the ranges of the optimal fence porosity are diversified among different research results, most ranging between 0.2~0.6, the reevaluated optimal fence´s porosity by PIV technology is 0.2~0.3. Fences with this range of porosity (between 0.2 and 0.3) have lower turbulence intensity in the leeside, the larger dissipation of wind energy, which can effectively controlled sand current. This belongs to the optimal fence porosity in theory, however, the fence porosity can always be broaden to 0.3~0.4 in practice to reduce its cost and without significant expense of shelter efficiency. Nevertheless, the complexity of flow over sand fences made the research of this problem use more simplification and hypothesis usually. Furthermore, people´s different comprehension and emphases on fences' sheltering degree made the standard of judges to be different, which led to the variety of optimal porosity of sand fences reported by investigators.
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Isogram of sheltering parameter around upright fence measured by PIV (Picture/Journal of Desert Research) |
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