On the Decay of Turbulence in the 20-Liter Explosion Sphere

The transient flow field in the standard 20-liter explosion sphere was investigated by means of laser Doppler anemometry. Velocities were measured at various locations within the flow field, and this information was used to quantify the transient behavior of the root-mean-square of the velocity fluctuations and to investigate the spatial homogeneity and the directional isotropy of the turbulence. The investigation involved the transient flow fields generated by the three most widely used dust dispersion systems, namely, the Perforated Dispersion Ring, the Rebound Nozzle, and the Dahoe Nozzle. With all three dispersion dust devices, the decay of turbulence could be correlated by a decay law of the formIt was found that no formal cube-root-law agreement exists between the 20-liter explosion sphere and the 1-m³ vessel. The results of this work also call into question the widely held belief that the cube-root-law is a valid scaling relationship between dust explosion severities measured in laboratory test vessels and the severity of industrial dust explosions. This revised version was published online in July 2006 with corrections to the Cover Date.