Research on the influence of roadway obstacles on the position of wind speed monitoring

The existing high-precision wind speed sensors are uniformly installed in the coal mines under normal airflow conditions. It does not consider the abnormal airflow caused by obstacles placed in the roadway. It cannot meet the wind speed precision requirements of intelligent ventilation and it is difficult to achieve safe production in the mine. In order to solve the above problems, taking the 11218 return air roadway of Xiaojihan Coal Mine as the research object, the influence of different positions and sizes of obstacles in the underground roadway on wind speed is studied. Based on on-site measured roadway basic parameters and Fluent software, a roadway model is constructed that fits the features of the mine. The influence of factors such as the distance between the obstacle placed on the floor at a distance of 10 meters from the upstream port and the two sides (referred to as the distance L), its shape, size, and position on the monitoring position of roadway wind speed is studied. ① The quantitative analysis results show that there are small reasonable wind speed regions at the right angles of the cross-section for each model. The maximum area is when L=0.5 m, followed by when L=1 m, and the minimum area is when L=0 m. As the distance L increases, the optimal placement position of the wind speed sensor follows a uniform distribution with the increase of the x-coordinate (roadway direction) - a trace distribution at the right angle of the cross-section - a hollow rounded rectangle distribution pattern. The reasonable airflow diffuses faster towards the two sides. When L=0 m, the reasonable airflow distribution of the vertical line in the roof position is at 2.59-2.78 m. When L=0.5 m, the reasonable airflow distribution of the vertical line in the roof position is between 2.59-2.80. When L=1 m, the reasonable airflow distribution of the vertical line in the roof position is 2.61-2.78 m. ② The qualitative analysis results indicate that the average wind speed in the roadway with obstacles is in a state of increase - decrease - increase - balance. The vertical placement or increase in width of obstacles has a significant impact on wind flow. The volume of obstacles is the same, and the peak wind speed is roughly the same. When the wind flow develops steadily, the wind speed reliability is highest at L=0.5 m, followed by L=1 m, and the reliability is lowest at L=0 m. ③ Through the analysis of wind speed universality, it can be concluded that under the same model, different wind speed change rates are in four stages of ascending - descending - ascending - balancing. Under the condition of model 2 and spacing L=0.5 m, the conclusion that the influence on the air flow transport law of the return air roadway is relatively small has wind speed universality.