Computational analysis of injection-velocity effects on dynamic parameters of unconfined fuel-vapor clouds

A computational investigation is performed to study the effects of injection velocity on the main dynamic parameters of the fuel cloud released into the open atmosphere. The volume, shape, and growth rate of the cloud, turbulence intensity, as well as the distribution of fuel concentration, temperature gradient, and self-ignition induction time are the most important parameters determining the mode of combustion that propagates through the cloud. A modified KIVA-based program is employed to fulfill the calculations. Systems of equations are solved by a finite-volume method. The $k$–$\varepsilon$ model and discrete droplet model are applied for modeling gas-phase turbulence and liquid spray, respectively. The fuel-injection velocity is shown to have a major effect on turbulence intensity and uniformity of the cloud. With increasing injection velocity, the detonable part of the cloud rotates sooner and faster, and there is less time for ignition. A comparison with experimental results is performed for validation.