Ignition Probability and Absolute Minimum Ignition Energy in Fuel Sprays

Abstract

Ignition in a one dimensional spray by a short duration source is modeled numerically. The probabilistic nature of spray ignition is discussed using a deterministic approach. The ignition source is modeled by a hot gas region of a defined thickness simulating a pilot flame or a low temperature spark source. For a given drop spacing, the location of the droplet closest to the ignition source determines whether or not the spray ignites. The bounds of droplet location beyond which the spray will not ignite define a droplet location domain for successful spray ignition. The ratio of length of this domain to droplet spacing is defined to be ignition probability. Ignition probabilities and ignition energies are presented for different ignition source thicknesses and overall equivalence ratios. The absolute minimum ignition energy is then obtained at the limit of zero probability. Temperature and fuel species profiles, along with droplet radii and location information, are also presented.

Key words:

• Ignition
• probability
• spray
• numerical