A spark ignition model for liquid fuel sprays applied to gas turbine engines

Abstract

The characteristic time model for ignition is used to describe the spark ignition of liquid fuel sprays in gas turbine combustors. The model states that for ignition to occur, the energy of a spark must heat up an initial volume such that the heat release rate within that volume is greater than the loss rate. Heat generation is limited first by a droplet evaporation time and then a kinetic time; heat loss (for gas turbine applications) is due to turbulent diffusion and, hence, is controlled by a mixing time. Data from two can-type combustors and seventeen fuels are correlated by a single ignition limit curve. The key to applying the model to engine data is the estimation of drop sizes and equivalence ratios at the spark gap.