Explosion Pressure and Flame Propagation Regularity of Aluminum Dust Cloud in Large and Medium-Scale Pipelines

In recent years, the frequency of aluminum dust explosion accidents in the industrial and trade sectors has increased, posing a serious threat to the safety of personnel and equipment. To investigate explosion pressure, flame propagation characteristics, and influencing factors of aluminum dust clouds in actual industrial pipelines, a medium-to-large-scale transparent pipeline metal dust explosion testing system was established. By monitoring explosion overpressure, time-pressure curves of the explosion at various points along the pipeline were obtained, and high-speed photography was employed to capture dynamic behavior characteristics of flame propagation in dust cloud explosion. Image processing techniques were employed to determine flame front propagation velocity under different concentrations and particle sizes. The results indicate that as concentration of aluminum dust cloud increased, explosion pressure at each measurement point significantly rose. Conversely, with increasing particle size, maximum explosion pressure markedly decreased, time to reach peak explosion pressure was prolonged, and pressure fluctuations became more pronounced before reaching the peak. Flame propagation in aluminum dust cloud explosions experienced three successive phases in different pipe segments: slow acceleration, rapid growth, and abrupt velocity changes, with flame front propagation velocity exhibiting a trend of pulsation, acceleration, and then pulsation again. This phenomenon can be attributed to the dynamic equilibrium of aluminum dust particles during endothermic and exothermic processes, as well as their interactions with combustion reactions. Additionally, localized turbulence and non-uniform distribution of dust cloud concentration were significant factors contributing to increased pulsation in flame propagation velocity. The findings of this study can provide a scientific basis and theoretical support for dust explosion prevention and mitigation in industrial production.