Unsteady, Spherically-Symmetric Flame Propagation Through Multicomponent Fuel Spray Clouds
The flame propagation through a fuel spray-air mixture in a spherical geometry is investigated by means of a one-dimensional unsteady analysis with a hybrid Eulerian-Lagrangian formulation. Finite-difference numerical schemes have been employed, with nonuniform grid spacing and an adaptive time step. Multicomponent sprays are considered. Emphasis is given to: the presence and role of diffusion and premixed flames; the movement of the droplets due to the expansion of hot gases and the resulting stratification; the effect of rapid vaporization of more volatile components; and the influence of the droplet size on droplet time history in a spray flame. More volatile fuels produce faster flame propagation. Nonuniform vapor fuel composition is generated due to the different volatilities of the components of the liquid fuel spray. Increasing the droplet size causes strong local deviation from the initially uniform equivalence ratio, due to the relative motion of the two phases. Flames generally have complex premixed and diffusion structures. Emphasis is given to flames propagating through unconfined domains.
KeywordsDroplet Size Flame Propagation Premix Flame Spray Flame Fuel Spray
Unable to display preview. Download preview PDF.
- Aggarwal, S.K., Fix, G.J., Lee, D.N., and Sirignano, W.A., 1983, “Numerical Optimization Studies of Axisymmetric Unsteady Sprays,” J. Comput. Phy., 35, 229.Google Scholar
- Aggarwal, S.K., and Sirignano, W.A., 1989a, “Ignition of Fuel Sprays: Deterministic Calculations for Idealized Droplet Arrays,” 20th Symposium (International) on Combustion, The Combustion Institute, 1773–1780.Google Scholar
- Continillo, G, and Sirignano, W.A., 1988, “Numerical Study of Multicomponent Fuel Spray Flame Propagation in a Spherical Closed Volume,” 22d Symposium (International) on Combustion, The Combustion Institute, 1941–1950.Google Scholar
- Sirignano, W.A., 1988, “An Integrated Approach to Spray Combustion Model Development,” ASME Winter Annual Meeting, Dec. 7–12, 1986, Anaheim, Calif.; also, Combustion Science and Tech. 58, 1–3, 231–251.Google Scholar
- Rangel, R.H., and Sirignano, W.A., 1989b, “Unsteady Flame Propagation in a Spray with Transient Droplet Vaporization,” 22d Symposium (International) on Combustion, The Combustion Institute, 1931–1940.Google Scholar
- Williams, F.A., 1985, Combustion Theory, Benjamin-Cummins, Palo Alto, Calif.Google Scholar