Study On Influence Of Air Duct Outlet Parameters Changing On Dust Field Distribution In Fully Mechanized Heading Face

In recent years,with the continuous breakthrough of the section size,driving speed and roadway length of fully mechanized heading face,which cause the dust production and the dust explosion accidents and pollution risks are increasing.The diameter,that angle and the front-back distance of the air outlet can not be changed in time,resulting in the airflow distribution in the roadway is unreaonable,and the ventilation requirement can not be met.Aiming at that problems existing in the ventilation in fully mechanized heading face.The influence law under different the distance from the air duct outlet to heading face,the diameter and the angle of the air outlet on the dust distribution are analyzed by underground actual measurement,the sample data of the relation between the air outlet parameters an the dust concentration is obtained,the concentration prediction model of the influence of the change of the air outlet parameters on the dust distribution is establishied by using the multiple regression analysis method.Then the dust falling effect is analyzed,which provides a theoretical basis for realizing the safety and green ventilation is fully mechanized heading face.Specific research contents are as follow:(1)The analysis on hydrodynamic theory of airflow field and dust field.The formation mechanism of air flow in each area of dust are analyzed.The laws of mass conservation,energy conservation and momentum conservation are adopted to analyze the airflow distribution.The the DPM discrete phase model is used to analyze the dust concentration distribution,which makes the theoretical foundation basis for the study on the influence of air outlet parameters on distribution.(2)Establishment of numerical simulation scheme of airflow field and dust field and the experimental verification study.Through the analysis of the actual ventilation environment and dust production situation in the fully mechanized heading face,the numerical simulation scheme of airflow field and dust field are established.Taking the specific fully mechanized heading face as the research object,and the numerical simulation calculation of airflow field and dust field are carried out by FLUENT software.The measured data and numerical simulation results of axial velocity of duct and dust concentration along the walking line in the backflow area are compared and analyzed.Then the feasibility of the numerical simulation scheme are verified.(3)Study on numerical simulation and regression sample data acquisition for the influence of air duct outlet parameters changing on dust field.The dust distribution law under the original ventilation condition is analyzed by using the verified numerical simulation scheme.Aiming at the existing problems,the dust field simulation schemes under the changing of the distance from outlet to heading face,diameter and angle of the outlet are designed.Then the influence law of the air outlet parameter changing on the dust distribution are analyzed,and sample data of the relationship between the airflow parameter changing and the dust concentration are obtained.(4)Forecast model establishment and dust effect of the influence of air outlet parameters changing on dust concentration distribution.By using of the obtained sample data,a dust concentration forecast model of the key position of the roadway safety hazard and the height of the driver breathing zone at the distance of the air outlet from the heading face is 5 m and a dust concentration forecast model of the key position of the roadway safety hazard and the height of the driver breathing zone at the distance 10 m are established by using a regression method.The dust concentration at the key position of roadway safety hidden danger and the height of driver's breathing zone is obviously reduced after adjustment and control,which provides a theoretical basis for the air outlet airflow adjustment and control for the optimal dust concentration distribution reality.