Study On Flow Field And Control Of Long-short Ventilation Dust In Fully Mechanized Head Face

In recent years,with the improvement of the level of mechanization of domestic coal mines,the comprehensive excavation face is one of the areas with the most serious dust pollution in coal mines.Controlling the dust source of the comprehensive excavation work not only can quickly reduce the dust concentration in the roadway,but also control the movement of dust particles in the roadway area and discharge the dust particles into the working area.Long-pressure short-pumping and mixed ventilation is the main ventilation method to ensure the safe production of underground mines and improve the working conditions of mines.It is of great significance to timely eliminate and prevent dust and toxic and harmful accumulation in comprehensive roadway.The paper combines the dust-related theory to study the dust-producing mechanism of the digging face and the main factors affecting the dust production.It is known that the dust mainly comes from the operation of the excavation machine.In addition,using aerodynamics,computational fluid dynamics and mine ventilation theory,numerical simulation and laboratory research methods,the movement law and wind flow of dust particles in wind current are studied and analyzed under the long-short and shortventilation mode of comprehensive working face.The flow field distribution and the optimal ventilation and dust reduction parameters provide effective theoretical support for the rational arrangement of ventilation systems in the actual mine roadway.According to the theory of jet flow and the characteristics of long-short and short-flow ventilation flow field,a simplified physical model of long-short-pumping mixed ventilation system for fully mechanized excavation face is established.The FLUENT software Realizable model is used to iteratively calculate the long-short and short-flow ventilation flow field and the SIMPLE algorithm is used to calculate the distribution of the simulated long-short and short-flow ventilation flow field.Through the numerical simulation of the wind flow field in the fully mechanized excavation face,it is concluded that the reasonable position of the air duct can reduce the accumulation of dust in the head area and enhance the entrainment of the draft tube,thereby improving the dust removal effect and laying a technical foundation for more efficient dust removal.Based on the actual coal mining face data,the boundary conditions and dust source parameters are determined,and the discrete phase model is applied to simulate the dust migration law in the roadway of the fully mechanized excavation face.The results show that when the long-short,short-pumping and mixed-ventilation medium-injection type air duct is separated from the comprehensive excavation working face,the dedusting effect of the extraction type air duct is less than m.Therefore,after reasonable ventilation,it can prevent high-concentration dust powder and discharge dust in time,and the effect of ventilation and dust removal is the best.According to the similarity theory,a similar experimental model of long-pressure shortdraw ventilation was established in the laboratory.The experimentally measured operating parameters were compared with the optimal parameters obtained by numerical simulation.it is good.It is proved that the numerical simulation of the long-shrinking and ventilation system of the fully mechanized excavation face and the reasonable working condition parameters are true and reliable,providing a reliable technical basis for underground dust prevention.