Experimental study on the overpressure and flame propagation of hybrid hydrogen/aluminum dust explosions in a square closed vessel

摘要

The overpressure and flame propagation of hydrogen/aluminum dust hybrid explosions are studied in a 5-L square closed vessel. Aluminum dust was mixed with hydrogen with concentrations of 0%-30%. The results show that there are certain hydrogen concentrations that affected the changing trend of the maximum pressure rise P-ex and the maximum rate of pressure rise (dP/dt)(ex). When the hydrogen concentration is lower than the certain concentration, the P-ex and the (dP/dt)(ex) are approximately equal to those of pure aluminum dust. When the hydrogen concentration is higher than the certain concentration, the P-ex and the (dP/dt)(ex) increase notably. As the hydrogen concentration increase to more than 20%, the flame front separation can be observed. The addition of hydrogen can significantly affect the ignition delay time and the flame propagation velocity of the hybrid mixtures. There are three stages in the relation of the maximum flame propagation velocity v(max) with the hydrogen concentration: in the first stage, the v(max) is almost equivalent to that of pure aluminum dust. In the second stage, the v(max) increases slightly. In the third stage, the v(max) increases significantly, which can exceed more than 50 times the vmax of pure aluminum dust.