The characteristic time model for ignition is used to correlate the spark ignition limits of fuel sprays in gas turbine combustors. The correlations are based on ignition data from several fuels in the JP-4 to JP-8 specification range and six gas turbine combustors. In the model, the criterion for ignition is that the spark energy 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 droplet evaporation and then the rate of hydrocarbon oxidation; heat loss is controlled by the rate of mixing (eddy diffusion). Conceptually, the rates are expressed as characteristic times in order to illustrate the relative importance of each process in the ignition event. Ignition limit correlations are given for each combustor as well as a single correlation of 322 data for four engines combined.

Volume Subject Area:
Combustion and Fuels
Topics:
Fuels, Gas turbines, Ignition, Combustion chambers, Heat, Diffusion (Physics), Drops, Eddies (Fluid dynamics), Engines, Evaporation, Heat losses, Oxidation, Sprays
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