Effect of aviation fuel type and fuel injection conditions on non-reacting spray characteristics of a hybrid airblast fuel injector

Injector spray characteristics have a signiffcant inuence on the combustion performance in a gas turbine engine, including a signiffcant impact on dynamics, emissions and component life. The introduction of sustainable alternative aviation fuels has made the spray characterization of these fuels before they are certiffed for engine service necessary. The present work describes the detailed characterization of several alternative fuels using a hybrid airblast atomizer on the basis of spray shape, droplet size and velocity distribution at a range of operating conditions including fuel temperature, injector pressure drop and spray chamber pressure and temperature. The characterization is done using optical patternation, phase Doppler anemometry (dual-PDPA) and high speed back-lit imaging. The measurements obtained as part of this work provide the validation data-set for computational modeling of the spray behavior which forms critical part of the broader project. The results show a strong inuence of the fuel temperature on the spray, with lower temperature (290 K to 240 K) decreasing the atomization quality by 17%. While the effect of fuel injection of the spray is minimal, a large effect of pressure drop across the injector is seen on the spray, with a change from 2% to 6% leading to a decrease in drop size of up to 35% which can result of a shift in the secondary breakup regime of the spray.