Turbulent flame propagation in large dust clouds

In order to be able to model correctly dust explosion propagation, data are needed to couple the flame velocity to the characteristics of the turbulence: intensity,u', and integral scale, Lt. So far most of the available data were obtained with laboratory equipments. In this paper, a few large scale experiments (up to 100 m3) were performed during which both the flame velocity and turbulence characteristics were measured. The results confirm a nearly linear dependency of the turbulent burning velocity, St, with u' but also with Lt. Surely further data are required but if the linear dependency of St with Lt is confirmed this would mean a significant difference as compared with premixed gaseous flames. It is suggested that this could be the consequence of the strong dust concentration gradients appearing systematically in turbulent dust clouds.