| The pollution caused by a large number of dust produced by coal breaking through cutting head of combined driving has caused great importance by domestic scholars.Due to the structural shape of the narrow and long roadway in the underground mine,it is difficult for the dust suspended in the air to diffuse.Thus,it pollutes the entire roadway along with the air flow inside the roadway,which is difficult to remove in time and seriously endangers human health.Moreover,dust had the risk of explosion,which will cause more serious casualties and property losses.Therefore,it is of great significance to adopt proper treatment technology and effective dusts control equipment to prevent the pollution brought about by flour dust pollution caused by combined driving.In order to solve the above-mentioned problems,theoretical analysis,numerical simulation and experimental study are combined,and the new theory of pneumatic vortex fog curtain control is studied systematically in this paper.The main research results are as follows:In accordance with the theory of rotary jet flow and liquid spray,the principle and method of pneumatic vortex fog curtain control are put forward and designed.That is to say,the inner ring air jet is used as the power to impact the outer ring high-pressure water spray with the impact effect of the rotating air curtain,which increases the droplet kinetic energy and improves the secondary crushing performance of fog droplets.At the same time,the formed aerodynamic vortex fog curtain can completely close the roadway and effectively improve the working range and economy of fog curtain.Droplet diffusion in wind velocity field of vortex jet is a comprehensive research topic.In this paper,a gas-particle phase turbulence kinetic model for simulating droplet motion is established by using the droplet atomization and fragmentation model of liquid flow module in COMSOL simulation software and combining with the linear multi-scale k-? turbulence model.The velocity distribution law of gas phase flow field and the influence law of jet velocity on atomizing radius,droplet velocity and particle size distribution were obtained by calculation and solution.The interphase flow pattern between vortex jet field and high-pressure spray and the atomization interference process are revealed in detail.The atomization performance and dust control performance of the pneumatic vortex fog curtain were studied and analyzed by using the self-built similar experimental model of the pneumatic vortex fog curtain dust control system.The atomization performance experiment explored the function relation and influence rule of ejector air velocity,atomization pressure and nozzle working Angle on atomization performance,and determined the basis for selecting atomization performance parameters.The results illustrates that the atomization radius increases with the increase of jet velocity,decreases with the increase of spray pressure,and increases with the first and then decreases of nozzle working angle.The experimental results of dust control performance reveals that the selection of reasonable atomization parameters can take into the shape of a complete rotating fog curtain closed working area to isolate coal dust pollution,and have a better effect on dust collection.A dynamic model of particle transport in underground roadway including tunneling system is established,and the transport law of gas phase flow field and dust field under different wind speed is simulated and analyzed.The formula of dust concentration distribution above 50mg/m3 at different height and wind speed was derived.What's more,on the basis of the obtained dust diffusion law,a combined dust control system of pneumatic vortex fog curtain control system and local ventilation device is designed.Proper atomization parameters are selected to simulate and analyze the pneumatic vortex fog curtain comprehensive dust control system.The motion process of droplet particles in rotating fog curtain of combined dust control system under different ventilation conditions is simulated and analyzed.When the pressure-wind combination Qp is greater than 4m3/min,and the long pressure and short pumping Qp is larger than 3m3/min,the formation of aerodynamic vortex fog curtain will be destroyed.The simulation results of the combined atomization interference experiment are compared with the simulation results to check the accuracy of the simulation results of the combined dust control system.The influence of ventilation system on the dust removal efficiency of joint dust control system is fully reflected by measuring the dust removal efficiency.The combined dust control system has a remarkable influence on dust collection,which proves the feasibility of the new equipment and provides theoretical support for the popularization and application of the new dust removal technology.There are 68 papers,14 tables and 167 references in this paper. |
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