A novel model for rapid correcting airflow velocity in semicircular arch tunnel of coal mine

Abstract

Accurate determination of air quantity delivered in underground coal mine tunnels is essential to ensure that the ventilation system is underground normal operation. Currently, the location of airflow velocity sensor hanged up in the semicircular arch tunnels of an underground coal mine is only based on a miner's experiences. Then, by comparing the velocity records obtained from sensors with ventilation engineers' onsite measurements, a set of correction factors are determine to correct and to derive the "real" airflow velocity. Apparently, this method is deeply subjected to the accuracy of onsite measurements and is prone to result in serious errors, and then to degrade the reliability of underground monitoring system. Therefore, the research works conducted in this paper aims to develop a fast and reliable model to rapidly correct the airflow velocity of semicircular arch tunnels in underground coal mines. By using theoretical analysis, numerical simulation and field experiments, the air velocity distribution pattern in the semicircular arch tunnel is investigated. The relationship between the point-monitored airflow velocity and the cross-sectional average velocity is analyzed. Then, a model with the error less than 5% for rapid airflow velocity correction is proposed, which ensures that the "real" average air velocity in the tunnel can be accurately obtained by using the point-monitored velocity after correction.