Macroscopic spray performance of alternative and conventional jet fuels at non-reacting, elevated ambient conditions

Gas-to-liquid (GTL) jet fuel, a liquid fuel synthesized from natural gas, has recently gained significant global attention due to its cleaner combustion characteristics when compared to the conventional jet fuels. The critical physical and chemical properties of GTL fuels are different from those of the conventional fuels, which in turn, influence the atomization, combustion, and eventually, the emission characteristics of the fuel in a jet engine. To this end, this work investigates the non-reacting near-nozzle spray performance of GTL and conventional Jet A-1 fuels using a pressure-swirl nozzle at elevated ambient conditions, which are relevant to practical combustors in a jet engine. The macroscopic spray features, such as spray cone angle, liquid sheet dynamics, and the sheet velocity, are determined using the high-speed imaging and shadowgraph technique. The ambient gas pressure is varied from 100 to 1300 kPa, and the ambient gas temperature is varied from 300 to 375 K, while the pressure difference across the nozzle is kept constant, in order to study their effect on the spray characteristics. The results show that the ambient gas pressure has a significant impact on the spray dynamics when compared to that of the ambient gas temperature, in the range examined in this work. The comparison of macroscopic spray results between the conventional and alternative jet fuels shows that the far-field spray cone angle for the GTL jet fuel is higher than those of the Jet A-1 fuel. Furthermore, in the near nozzle region, the sheet breakup region for the GTL jet fuel is slightly longer than that of the conventional fuel under the conditions studied.