Fuel and Operating Condition Effects on Lean Blowout in a Swirl-Stabilized Single-Cup Combustor

Abstract

As alternative jet fuels are introduced into the market, understanding operability limits, in particular the lower stability limit, becomes imperative for safety and the approval of these new fuels. Previous experiments have indicated that at elevated temperatures, lean blowout limits in a single-cup, swirl-stabilized combustor (referred to as the referee combustor) were highly correlated to fuel chemical properties. Low pressure and low temperature experiments also performed in the referee combustor demonstrated physical property dependency due to poor atomization. This agreed with trends seen in an auxiliary power unit (APU) at similar pressure and temperature conditions. Four fuels with varying physical and chemical properties were observed at intermediate conditions of Tair = Tfuel = 305-355K, P = 107kPa, and ΔP/P = 2-6% to examine fuel property and operating condition effects on physical and chemical property dependence. Change over from physical to chemical property dependence was found to occur over a range of conditions rather than a single temperature point. Changes in pressure drop across the combustor dome were found to change the relative LBO limits of the fuels, and demonstrated a change from physical to chemical property dependence. Analysis via random forest regression demonstrated that an approximate Weber number was the strongest parameter to correlate fuel properties to combustor LBO.