Potential alternative fuels that can mitigate environmental pollution from gas turbine engines (due to steep growth in the aviation sector globally) are getting significant attention. Spray behavior plays a significant role in influencing the combustion performance of such alternative fuels. In the present study, spray characteristics of Kerosene-based fuel (Jet A-1) and alternative aviation fuels such as butyl butyrate, butanol, and their blends with Jet A-1 are investigated using an air-blast atomizer under different atomizing air-to-fuel ratios. Phase Doppler Interferometry has been employed to obtain the droplet size and velocity distribution of various fuels. A high-speed shadowgraphy technique has also been adopted to make a comparison of ligament breakup characteristics and droplet formation of these alternative biofuels with that of Jet A-1. An effort is made to understand how the variation in fuel properties (mainly viscosity) influences atomization. Due to the higher viscosity of butanol, the SMD is higher, and the droplet formation seems to be delayed compared to Jet A-1. In contrast, the lower viscosity of butyl butyrate promotes faster droplet formation. The effects of the blending of these biofuels with Jet A-1 on atomization characteristics are also compared with that of Jet A-1.

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Biofuels are carbon-neutral alternative fuels, which have emerged as an important source of energy for the aviation industry to reduce greenhouse gas emissions. Butanol is considered an emerging biofuel with properties that are suited for application in gas turbine engines. It is traditionally produced through the fermentation process of biomass (acetone-butanol-ethanol fermentation). To examine the feasibility of butanol as operating fuel, the combustion characteristics of butanol and butanol/Jet A-1 blends are examined in a labscale swirl stabilized burner, with emphasis on the effect of preheating because of the variation of inlet air temperature during flight operation. To rich the constant air temperature to 150 C, the incoming air (main air) is preheated and investigated for various equivalence ratios. Compared to neat Jet A-1, the flames of the butanol/Jet A-1 blends have shown a better effect on global emission characteristics with comparable temperature distribution on adding butanol to Jet A-1. A 50% butanol-loaded blends show a reduction of 29% CO and 24% NOx compared to neat Jet A-1 whereas 30% loading follows a similar trend, and the pollutant emission is slightly higher than the 50% blend case.Additionally, both 30% and 50% butanol blends show a comparable flame temperature distribution, which is higher than neat Jet A-1.

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