Numerical Simulation On Non-uniform Porosity Design Optimization For Porous Fences

Porosity is the most important factor influencing the effect of dust suppression due to its influence on the turbulence structure behind the windproof dust suppression network.The study of the optimal porosity has become one of the most direct and effective ways to improve the dust suppression effect of the wind and dust suppression network.At present,the physical mechanism of the air flow under the uniform porosity and the force acting on the surface of the pile has provided strong theoretical support for the determination of the optimal porosity.The results also show that even if the uniform porosity of the surface of the pile off the bulk dust characteristics Also based on the location,this paper bases on the theoretical basis of the porosity to determine the flow field structure around the stockpile.Different porosity has different flow characteristics at different positions on the surface of the stockpile,resulting in different rules for dust suppression effect.Explore the different porosity combination stockpiles The porosity distribution with the best dust suppression effect on each surface,and the surface shear force as the basis for measuring the dust suppression effect,studied the movement characteristics and dynamic characteristics around the windrow and dust suppression net under different porosity combinations,and calculated the optimal porosity.Rate combination;based on vertical and vertical porosity combination research,the dust suppression effect of pile side net porosity under different nets is discussed.After verifying the numerical simulation,the following main conclusions are obtained:?1?Fluent software was used to simulate the wind speed at 6m/s for the incoming wind,and the normal wind speed,surface pressure of the stockpile,relative wind speed at different heights,and stockpile on the surface of the stockpile under the seven typical conditions of the three-hole non-uniform net.The microscopic characteristics of the surface pressure coefficient,turbulent kinetic energy,etc.,obtained that the porosity in the middle and the lower part of the net is constant,the porosity in the online part increases from 0 to 0.1,the vertical pressure difference before and after the net decreases,and the disturbance of the net airflow weakens.The relative wind speed on the near wall is reduced and the dust suppression effect is good.When the on-line porosity??_H?is taken as 0.1,the dust suppression effect is good;the porosity on the upper and lower net parts is constant,and the porosity in the middle part of the net increases from 0.4 to 0.6.The windward surface of the stockpile is changed from sticking flow to mixed flow of vortex flow and adhering wind.The wind speed near the wall surface of the windrow increases,the airflow disturbance increases,the dust from the stockpile increases,the integrated vortex range and turbulence structure,and the central porosity??_M?are good at 0.4;the porosity of the net and the middle of the net is constant,and when the porosity of the lower part of the net increases from 0.2 to 0.4,the infiltration in the middle of the net increases,the infiltration wind increases,and the strength of the attached stream on the windward side of the stack increases.Relative to the near wall When the wind speed increases,the pressure difference on each surface of the stack increases,and the dust in the stack increases.When the porosity of the lower part of the porosity??_L?is 0.2,the wind and dust suppression effects are the best;comprehensive consideration of the online,middle,and lower porosity?_H/?_M/?_L=0.1/0.4/0.2,the dust suppression effect is best.?2?Analyze and compare the dust suppressing effects of uniform net,two-hole non-uniform net,and three-hole non-uniform net dust suppression net.The results show that the effect of three-hole non-uniform net dust suppression is mainly reflected in the wind shear on the stockpiles.Reduction of force,when the three-hole non-uniform mesh?_H/?_M/?_L=0.1/0.4/0.2,the shear force on the windward side decreases by 80%compared with the two-hole non-uniform meshes?_H/?_L=0.1/0.3.The ratee=0.3 is reduced by 89%;but the three-hole non-uniform mesh top surface shear force is increased compared with the two-holenon-uniformmesh,andthethree-holenon-uniformmesh?_H/?_M/?_L=0.1/0.4/0.2 each surface shear The shear force ratio is reduced by 66.1%compared with the uniform meshe=0.3,which is reduced by 31.2%compared to the two-hole non-uniform mesh?_H/?_L=0.1/0.3.The shear strength of each surface of the three-hole heterogeneous mesh pile is absolute.The sum of the values is the smallest and the dust suppression effect is the best.?3?Studying the change of shear force on each surface of the pile and the microscopic dynamic distribution of the surrounding air when the porosity of the pile before the net and the porosity of the side net of the pile are set on the three sides of the pile.When the porosity of the mesh is 0.4,the change of the porosity of the side mesh has a great influence on the lateral shear force of the pile,while the influence of the shear force on the windward side,the flat top side and the leeward side of the stockpile is small,?₁/?₂=0.4/0 the lateral shear force of the stockpile is maximum,and when the porosity of the side net increases from 0 to0.5,the lateral shear force of the stockpile first decreases and then tends to be flat.When the porosity of the side net increases from 0 to 0.3,the side net infiltration increases,the proportion of infiltration wind increases,and the pressure difference before and after the net decreases.The obstruction of the flow through the side net to the flow of the reactor makes the side surface of the stack near the wall As the wind speed decreases and dust is reduced,when the porosity of the side net increases from 0.3 to 0.5,the inhibition effect of the lateral flow permeation of the stack on the flow of the reactor is not obvious,and the lateral shear force of the stack is less changed.In this paper,the motion characteristics and dynamic characteristics around the wind-resistant dust suppression network are studied under different combinations of porosity,and the optimal porosity distribution of the wind-proof and dust-reducing network is obtained by using the minimum sum of shear forces on each surface of the pile as the criterion.It provides a new technical method for the optimal design of wind and dust suppression nets.