Study On The Coupling Characteristics Of Airflow And Gas In Tunnel Section With Different Shapes

In the coal roadway,the flow field and the gas concentration field are interrelated and interact with each other to form a complex coupling relationship.This coupling characteristic directly affects the distribution characteristics of the gas in the roadway.The more clear the characteristics of the distribution of gas in the roadway,the more accurate the implementation of the gas control measures.Therefore,it is of great theoretical and practical value to study the airflow-gas coupling characteristics in different section roadways,And gas control to provide a more complete theoretical guidance.The main research contents of this paper are the distribution of wind speed in different shapes of roadway sections,the law of gas concentration distribution and the characteristics of airflow-gas coupling.The main conclusions are as follows:(1)The simulation experiment of wind speed wind tunnel in semicircular arch roadway section is carried out,and the eight characteristic lines on the measured flow field of the test section are selected to carry out the non-uniform arrangement point.By comparing the thickness of the boundary layer atdifferent center points,the wind speed is in the range of 0.99 ~ 8.46 m / s,and the wind speed at the center point of the tunnel section has little effect on the thickness of the boundary layer.When there is no obstacle in the semi-circular arch wind tunnel simulation,the wind velocity distribution shows a difference between the upper and lower symmetrical upper and lower.In the center of the roadway for the symmetrical point up and down symmetrical position,the lower part of the speed was significantly higher than the upper.(2)In order to master the distribution of the ventilation flow field and the gas concentration field in the general roadway with different shapes,the numerical simulation of the most commonly used computational fluid dynamics software Fluent is carried out.The innovation of this paper is to make the coal wall of the two roads in the roadway and make the gas emission of the coal wall with the porous media model.Then,the flow control parameters of the three models are simulated and calculated by using the control parameters.Tecplot postprocessing the simulation results.The simulation results show that the contours of the wind speed distribution are approximately arched,rectangular and trapezoidal,respectively.It can be seen that the contours of the velocity on the section are related to the shape of the section.The contours of the contours of the arched roadway are raised,while the contours of the rectangular roadway and the trapezoidal roadway are recessed.When the wind speed increases or the gas concentration decreases,the contours of the contours will decrease or even disappear;when the wind speed decreases or the gas concentration increases,thecontours of the contours will become more pronounced.The gas concentration distribution in the three sections is relatively regular,and the gas concentration and concentration gradient near the side wall of the roadway are the largest in the horizontal direction.The distance to the center of the roadway is getting smaller and smaller;the vertical concentration is close to the bottom,Approaching the roof is getting bigger and bigger.(3)The numerical simulation of the wind speed distribution in the rectangular roadway of the Yuwu coal mine is carried out.The simulation results are compared with the actual measured wind speed values.It is found that the measured wind speed value and the numerical simulation wind speed value in the central area of ??the roadway The wind speed value and the numerical simulation wind speed value in the same location are close to the edge of the roadway and the side wall of the pipeline.It can also be found that the numerical simulation of the wind speed near the bottom of the roadway is almost the same Which is larger than the measured wind speed value,and the numerical simulation given near the top of the roadway is almost the same as the measured wind speed value.