- Author
- Prasad, K. R.
- Title
- Optimizing Water-Mist Injection Characteristics for Suppression of Liquid Methanol Pool Fires. BFRL Fire Research Seminar. VHS Video.
- Coporate
- Naval Research Laboratory, Washington, DC
- Report
- Video, October 18, 1999,
- Keywords
- water mist | suppression | pool fires
- Abstract
- Numerical simulations have been performed to optimize water-mist injection characteristics for fire suppression. A mathematical model is first developed to describe the evaporation and burning of liquid methanol. The complete set of unsteady compressible Navier-Stokes equations for reactive flows are solved to describe the convection of fuel gases away from the pool surface, diffusion into the surrounding air and oxidation of the fuel molecules into product species. A two-continuum formulation is used in which the gas phase and the water-mist are both described by equations of the eulerian form. Computations have been performed to study the interaction of water-mist with pulsating pool fires. The relative contribution of various mist suppression mechanisms is studied. The effects of droplet diameter, mist injection angle (throw angle), mist density and velocity on entrainment and overall suppression are quantified. These results are reported in terms of reduction in peak temperature, effect on burning rate and changes in overall heat release rate. Numerical results will be presented for symmetric and asymmetric spray pattern geometries resulting from base injection and side injection nozzle orientation. Results indicate that smaller droplet diameters produce optimum suppression under base injection configuration, while larger droplet diameters are needed for optimum suppression for the side injection configuration. For all cases, the model is used to determine the water-mist required for different levels of suppression, and this is reported in terms of the ratio of the water-mist supply rate to the fuel flow rate.