Study on ignitability of fuel spray

Abstract

Effects of droplet diameter, liquid and vaporized fuel concentration on the ignitability of fuel spray were investigated. A large number of ignition trials of various methanol liqui/vapor/air mixture were carried out. As a result, ignition probability increases with the increase of the liquid and vaporized fuel concentration and decreases with the increase of droplet diameter. The particular condition exists which fuel spray is not always ignited successfully even if the total fuel concentration is higher than that of lean ignition limit of vaporized fuel. In addition, simple probabilistic-ignition model that based on the fluctuation of spray concentration is applicable for macroscopic evaluation of ignition phenomenon. However, from the result of instantaneous liquid fuel concentration measurement, the assumption of probabilistic model, i.e., ignition is deterministic by the instantaneous liquid fuel concentration just before ignited, is not adequate for microscopic evaluation.