Research On Wind Speed Distribution And Accurate Air Flow Monitoring In A Typical Roadway Section

Ventilation is the cornerstone of coal mine safety production.Accurate monitoring of ventilation parameters is the basic guarantee for ventilation technology decision.For the problem that the accuracy of coal mine tunnel wind speed monitoring is difficult to meet the needs of decision-making,this paper uses theoretical calculations,numerical simulations,laboratory tests,and industrial verification.Combined with the method,the positional relationship between the average wind speed line and the wall surface of the shaft is studied,the distribution law of the wind speed in a typical roadway section is simulated,and a set of precise layout methods for downhole wind speed sensors is proposed.The main results are as follows:(1)The main factors influencing the distribution of the wind speed of the roadway section are analyzed: including the shape of the roadway section,the size of the section,the form of support,the size of the wind speed,the status of facilities and equipment,etc.(2)It is calculated that the positional relationship between the average wind speed line of the rectangular and semi-circular arch roadway and the wall surface of the roadway are both.The calculation results show that the location of the average wind speed line of the tunnel is only related to the cross-sectional size of the tunnel,and is not related to other main control factors.The distance between the average wind speed line and the two sides of the tunnel(top and bottom)is about 0.11 times the width(height)of the tunnel.In the center of the roof of the roadway,it is 0.11 times the height of the roadway from the top of the roadway.(3)The simulation has obtained the distribution law of the wind speed of different types of tunnel sections under different conditions.Through the 25 sets of models,the wind speed distribution characteristics of the tunnel cross-section are obtained:(1)the contour of the wind speed is basically parallel to the wall surface of the tunnel;Large and reduced.(2)The gradient of wind speed near the wall of the tunnel is large,and the gradient of wind speed in the middle of the tunnel is small;(3)The thickness of the boundary layer decreases with increasing wind speed.(4)The reliability of the theoretical calculation and numerical simulation results was verified in the laboratory and the field.Using the proposed multi-section mirrorladder network format inspection method,8 groups of tunnel airflow fields under different conditions were measured in the laboratory and coal mine site,and the contour map of wind speed distribution was drawn to obtain the measured average wind speed line position.The absolute error of the calculation result with the theoretical model is within 5%.(5)A method of arranging sensors on the tunnel average wind speed line to achieve accurate monitoring of the tunnel air volume is proposed,and a monitoring validity judgment method is obtained through research.The wind speed sensor is arranged at the height of the tunnel on the central axis of the tunnel at a distance of0.11 times the roof,which can realize the effective and accurate measurement of the tunnel air volume.