| The dust in the open yard is one of the main sources of atmospheric environmental pollution.Effective prevention and control of dust pollution is of great significance to society and natural environment.This subject mainly focuses on the optimization design of the wind and dust suppression net,and explores the influence of the distance between the wind and dust suppression net and the pile,and aperture of wind and dust suppression net to Characteristics of flow field around the pile and surface shear force characteristics of the pile.Finally,the optimization plan of the wind and dust suppression network was selected.This subject mainly uses CFD technology for numerical simulation,the ANSYS Workbench software was used to construct the three-dimensional geometric model and the grid division.The fluent was used as the solver for the calculation and a grid independence was verified.The software such as Tecplot and Origin were used for data processing.The content of numerical simulation includes the influence of wind speed on the air flow field characteristics of the prism-shaped pile without windproof dust suppression net,and the influence of the optimized design of the windproof dust suppression net on the dust emission characteristics of the pile,and the influences of shape of the pile on the surrounding air flow field.Finally,the numerical simulation results are verified.The following conclusions are obtained:(1)Based on the three-dimensional physical model of the circulating yard,the effects of the five wind speeds of 2.5m/s,3m/s,5m/s,7m/s,and 9m/s on the air field around the pile without windproof dust suppression network were simulated.The numerical simulation results show that: under different incoming wind speeds,the relative value distribution of the wind speed on the surface of the pile was basically the same;along the windward side,as the height increases,the dusting phenomenon was more obvious,the shear force was the largest at the top of the pile,and the wind speed Larger,the greater the increase in dust generation.In the case of low wind speed,the shear force on the flat top surface changes gently.At high wind speed,the shear force in the first half is strong,and the latter half is smooth and tends to be stable.The vortex on the leeward surface was caused by negative pressure;(2)The dust change of the pile was mainly affected by the air flow pattern in the middle area of the windward surface of the pile and the pile and the flat top surface.When the aperture was 10 mm,the return vortex caused by the vertical pressure difference increases with the distance,which was 0.016 m,0.035 m,0.044 m in sequence;when the aperture was 20 mm,the return vortex caused by the vertical pressure difference The height of the spin center increases first and then decreases,which was 0.024 m,0.055 m,and 0.025 m in order.In the case of backflow on the windward side,the attachment flow on the windward surface will increase the wind speed at the top of the pile,and the pile was likely to dust.(3)From the point of view of pressure field,the change trend of pressure coefficient at φ / d = 20/60 and φ / d = 20/120 was similar to that at φ / d = 10/60,and both increase trend were first and then decrease and finally stabilized along the direction of incoming flow.The smaller the opening on the windward side,the smaller the absolute value of the pressure coefficient,and the smaller the impact on the dusting change of the downstream flat top surface.From the pressure distribution cloud diagram of the pile behind the wind and dust suppression network and the pressure coefficient distribution near the wall of the pile,when φ / d = 10/90,the pressure field near the wall of the pile was the most stable,and the dust emission of the pile does not change obvious.(4)From the perspective of the turbulent flow field,the high turbulent outflow behind the wind and dust suppression net was appeared at the position of the small hole.When the aperture is 10 mm,as the distance between the net and the pile increases,the turbulent field behind the net mainly diffuses downstream,the turbulent flow energy decays faster,and the turbulent energy on the windward side was relatively low.When the aperture is 20 mm,as the distance between the net and the pile increases,the turbulent energy on the windward side first decreases and then increases.When the distance between the fixed net and the pile is 90 mm,the turbulent energy on the windward side was gradually increased from the process of increasing the aperture from small.(5)From the perspective of surface shear force,when φ / d = 10/90,φ / d = 15/90,φ / d = 20/90,φ / d = 10/120 and below 9/10 near the top of the windward surface,the shear force was negative and increases gently.Changes of shear force of φ / d = 10/90,and φ / d = 10/120 were similar.Changes of shear force of φ / d = 15/90,and φ / d = 20/90 were similar.When approaching the top of the windward surface,the shear force was positive and gradually increases with height.(6)The results of the study on the effect of the distance between the wind and dust suppression net and the pile on the dust generation of the pile show that when the opening size of the wind and dust suppression net was fixed,the distance between the net and the pile was preferably 1.5 times the stack height.The degree of dusting increased from weak to strong as the pore size increased.(7)The research results of the impact of the pile shape on the dust generation of the pile indicate that the incoming air flows from the bottom of the pile to the top of the pile,and the wind speed gradually increases and reaches the maximum at the top of the pile.The change in wind speed at the flat top surface of the round table type pile was similar to that of the prism table type pile.A thin shear layer was formed on the flat top surface and compaired to the cone type,the horizontal wind speed was small.The wind speed is the highest at the top of the pile,the dust is the strongest on the windward side,and the dust is the weakest on the leeward side.The second is round table;The cone type has the lowest wind speed at the top of the pile,the weakest dust generation,and the strongest dust generation on the leeward side. |
