Computational Method Study On Drag Coefficient Of Porous Fence

Dust suppression engineering technology of porous fences is an effective measurement to control dust re-entrainment in a large open stockyard.The core component of the technology is porous fences,but force of porous fences has not yet formed a special specification.The value is directly related to the structural design of steel frame,which has important guiding significance for engineering construction.In this paper,using FLUENT software to simulate the influence of the porosity on the flow characteristics behind the planar and butterfly porous fence,and compared with the experimental data of PIV.The coincidence of comparison verified the reasonability and the correction of the numerical models.On these bases the numerical simulations of the wind speed,porosity and hole diameter on the force of the planar and butterfly porous fences were conducted.The results show:(1)The drag coefficient of the planar and butterfly porous fences decreases gradually with the increase of wind speed,and when the wind speed is greater than 10.0m/s,the drag coefficient does not change with the increase of the wind speed,taking into account the windbreak engineering construction,selection of wind speed is generally based on the local maximum wind speed in 50 years,and its value is usually greater than 10.0m/s.Therefore,the influence of the variation of wind speed on the drag coefficient is neglected;(2)When the wind speed and the hole diameter are the same,the drag coefficient of the planar porous fence decreases exponentially with the increase of the porosity,and its fitting formula: when d=6mm,0?(?)?0.353,cd=2.342(1-(?)2.652).When the wind speed and the porosity remain unchanged,the drag coefficient of the planar porous fence decreases nonlinearly with the increase of hole diameter,and its fitting formula: when 4mm? d ?12mm,cd((?)=0.264)=2.838-0.171d+0.0156d2- 0.00048d3;(3)The effect of the longitudinal distance of the butterfly windbreak on the drag coefficient is related to the porosity.In a small porosity,the influence of longitudinal spacing on the drag coefficient is less than the hole diameter of the drag coefficient,while the larger porosity,the influence of the longitudinal spacing on the drag coefficient is greater than the diameter of the hole diameter;the influence of the transverse spacing on the drag coefficient is less than the hole diameter;(4)In order to reduce the force of the butterfly windbreak,the butterfly windbreak with a larger hole diameter is optimized under the same mesh arrangement and porosity;(5)Based on the numerical results,the formula for calculating the drag coefficient of butterfly windbreak is obtained;When 6.6mm? d ?9.5mm,0?(?)?0.367 cd=k(?)+2.280;k=0.00185-0.030d-0.0067d2...