Effects of nanoscale fuel additives on properties and non-reacting spray performance of alternative, conventional and blended jet fuels at elevated ambient conditions

The dispersion of nanoscale metal particles in liquid hydrocarbon fuels, or nanofuels, has recently garnered interest owing to its positive influence on fuel emission characteristics. Physical properties of the fuel are altered due to the addition of nanoparticles, which in turn can affect its atomization, combustion, and emission characteristics. Therefore, a better understanding of the atomization phenomena is essential to recognize its influence on the combustion process. The objective of this work is to investigate the impact of alumina nanoparticles on the non-reacting spray characteristics of conventional Jet A-1, an alternative gas-to-liquid (GTL) fuel, and a 50-50% by-volume blend of these, each at elevated ambient conditions that are relevant to industrial applications. First, the influence of the nanoparticle addition on the fuel properties relevant to atomization is investigated. Then, the macroscopic spray characteristics, such as spray cone angle, liquid sheet dynamics, and liquid sheet velocity, are determined as a function of nanoparticle concentration, fuel type, and ambient pressure. For this purpose, an aviation-based pressure-swirl nozzle is used to generate the fuel spray with nanoparticle weight concentrations at 0, 2%, and 4%. The spray characteristics are measured at different ambient pressures of 100, 500, and 900 kPa, while the ambient temperature is maintained at an elevated 400 K for all the cases. The spray features of the above fuels with and without the dispersion of nanoparticles are compared. The macroscopic spray results demonstrate that the nanoparticle dispersion, even at low concentrations, can affect the spray in the near-nozzle region. The earlier disruption of the liquid sheet occurring with nanofuels indicates the influence of nanoparticles on the spray liquid sheet dynamics. Also, the results show that ambient pressure has a significant effect on the spray features for all three fuels studied.