Quantitative analysis of airflow velocity distribution and average wind speed line localization in irregular mine roadways

Accurate measurement of airflow velocity in mine roadways is critical for underground ventilation management, hazardous substance (methane, dust) migration control, and sensor optimization placement. However, turbulent flow dominance and cross-sectional irregularities (e.g., deformation, wall roughness) lead to complex spatiotemporal variations in velocity fields, posing great challenges to precise velocity estimation. To address this issue, this study systematically investigates airflow velocity distribution characteristics in irregular mine roadways using a combination of numerical simulation and field testing. First, Fluent software was employed to establish 3D models of semi-circular arch and trapezoidal roadways with different semi-circular convex radii (0-500 mm), cross-sectional dimensions, inlet velocities (0.5-8 m/s), and support types. Velocity distribution patterns in fully developed turbulent regions (120 m from the inlet) were analyzed, and nonlinear fitting was used to clarify the logarithmic relationship between point wind speed and distance from the roadway wall. The position of the average wind speed line was quantitatively determined: approximately 0.11 times the roadway width/height from the walls for regular cross-sections, and 0.1 times for irregular cross-sections. Field tests were conducted in Taoyuan Coal Mine, using a hot-wire anemometer (STA2) for point measurement and the traverse method for verification. Results show that the relative error between numerical simulation and field measurement is within 5%, confirming the reliability of the simulation model. This research provides a scientific basis for optimizing sensor placement and improving the accuracy of airflow velocity measurement in irregular mine roadways, contributing to the enhancement of underground ventilation safety and intelligent management.