Modeling transport phenomena of high mass loadings with applications to fire suppression

Abstract

Improvements to the existing Eulerian-Lagrangian two-phase dilute spray model, referred to as Vulcan, are required in order to handle high mass loadings or very small solid particles. Such flows are relevant to modern fire-suppression techniques among other applications. These improvements include developing a new treatment for efficiently integrating small particles, a new subcycling time-step selection algorithm for the time-splitting solution technique, and a new treatment for placement of the two-way coupling source terms on the fluid grid. Despite the added complexity of these modifications, performance tuning of the code was also performed so that the solution speed is either equivalent to or faster than the previous code, depending on particle size. The new algorithms are applied to predicting suppressant distribution from a Goodrich-244 fire-suppression system in a simulated aircraft cargo bay. Results using these new algorithms indicate that the larger particles found in the Goodrich-244 suppressant disperse more uniformly throughout the aircraft cargo bay, although a large fraction of these particles adhere to the side walls before being delivered to the fire. Buoyancy of the hot combustion products was found to inhibit particle dispersion, and to generate large unwanted convective heat fluxes to the roof of the cargo bay.