Computational Analysis of Ground Effects on the Dynamical Behavior of Unconfined Two-Phase Clouds in View of Detonability Studies

A numerical analysis has been performed to investigate the ground effects on the main parameters of a two-phase unconfined cloud of fuel and air to study its detonability. Equivalence ratio, turbulence intensity, cloud shape and volume, uniformity, temperature gradient and delay time distribution are the most important factors that affect the detonability of a vapor cloud. The effects of the altitude of the dispersing device from the ground on these significant factors have been demonstrated. A modified KIVA-based program has been employed to carry out the computations. A finite volume method is used to solve the equations describing the gas phase. A discrete particle technique is applied to represent the liquid spray and a k-\varepsilon model is used for modeling the gas phase turbulence. Theoretical considerations and comparison with associated experimental values were made for validation. As the injection height increases, the cloud becomes more uniform and the possibility of the pulsing propagation of the detonation wave decreases. When the injection height decreases, the contour of the detonable range rotates faster and delay time decreases. As a trade-off between all effective parameters, in this paper, an optimum for the injection height is introduced.