The Main Characteristics of Slow Coal-Dust Explosions and Their Relation of the Testing of Barriers

摘要

The main characteristics of slow coal-dust explosions in the new gallery at Buxton are a constant initial flame front acceleration from practically zero velocity up to a speed of about 120 m/s, followed by an increasing acceleration of the flame front. The initial acceleration is determined wholly by the effect of the igniter on the dust deposit and is made evident by plotting the square of the flame arrival time against distance, but the subsequent increasing acceleration is due to the flame of the explosion. This behaviour is found also in other experimental galleries where the ignition zone is short and where the main fuel in the ignition zone is the same as in the deposit in the rest of the gallery. The violence of an explosion can be characterized by the initial acceleration, which can be used to compare explosions in different galleries. The minimum acceleration that will sustain an explosion without oscillation of the flame along the gallery is inversely proportional to the length of the gallery; explosions in long underground roadways can accelerate more slowly without suffering oscillations than those in short experimental galleries, and this may be important in the siting of explosion barriers. (Author)