Static-Dynamic Coupling Model for Overpressure Propagation in Pipeline Coal Dust Explosions

To ensure safe production in coal mines and effectively mitigate casualties as well as economic losses caused by coal dust explosions, the overpressure propagation laws following explosions of coal dust with varying concentrations in a pipeline were investigated. Based on the positive feedback mechanism between the shock wave and the flame wave during coal dust explosions in a horizontal pipeline—realized specifically through heating and compression effects, a rigorous dimensional analysis method was employed. This method allowed a comprehensive consideration of a series of dynamic and static factors affecting the overpressure propagation of coal dust explosions, including energy of the explosive coal dust mixture, accumulated volume of the explosive coal dust mixture, pipeline cross-sectional area, hydraulic diameter, distance from the measuring point to the explosion source, initial air pressure before explosion, air density, coal dust concentration, flame propagation velocity at the measuring point, coal dust particle size, and pipeline friction coefficient. By incorporating experimental data, a dynamic-static coupling mathematical model was established to describe the unidirectional propagation of overpressure from coal dust explosions in a semi-closed straight pipeline. The model was subsequently validated and subjected to further comprehensive comparisons. The results clearly indicate that the energy of the explosive mixture, the distance between the measuring point and the explosion source, coal dust concentration, flame propagation velocity, and coal dust particle size constitute the main factors influencing the overpressure propagation of coal dust explosions. A strong positive correlation exists between coal dust explosion overpressure and flame propagation velocity. In practical hazard assessments of coal dust explosions, particular attention should be paid to factors that promote flame acceleration, such as turbulence and obstacles. The established dynamic-static coupling model demonstrates high reliability. Compared with existing overpressure prediction methods, this model offers lower operational thresholds and the capability to resolve the dynamic overpressure propagation process, thereby presenting overall comprehensive advantages.