Abstract

The demanding emission requirements must be satisfied by the modern aero-engines which led the researchers into exploration and development of environment-friendly, and sustainable aviation fuels. Water emulsification in fuels is a proven mechanism to reduce nitrogen oxide (NOX) and pollutant emissions. Furthermore, water addition in liquid fuel can improve the combustion performance and fuel economy by micro-explosions and puffing phenomenon due to the volatility difference between liquid fuels and water. These micro-explosions and puffing result in the breaking of fuel droplets into smaller droplets which promotes secondary atomization of the liquid fuels. The secondary atomization contributes to a higher combustion rate, improves fuel-air mixing, and thus improves fuel economy. Also, with the depletion of fossil-fuel sources, the scientific community is exploring renewable sources which can be both reliable and better substitutes for conventional fossil fuels. Blending biofuel with fossil fuel is an interesting way to a sustainable solution for green energy production and carbon footprint reduction of conventional aviation fuels. In these contexts, the present study reports an experimental investigation on the combustion characteristics of water emulsified Jet-A and water emulsified ethanol-blended Jet-A fuels. The Ultrasonication method is used to prepare homogenized fuel emulsions with three different water concentrations (2.5%, 5% & 10% by weight) for both Jet-A and ethanol-blended Jet-A fuels. Blended Jet-A fuels are prepared for different ethanol concentrations (2.5%, 5% & 10% by weight). Combustion characteristics such as ignition delay, combustion rate, and droplet burning time data are generated for each emulsified fuel. The results are compared for both Jet-A, and ethanol-blended Jet-A fuel emulsions. It is found that there is a general decrease in combustion rate and droplet burning time for all the emulsions. This decrease is higher with higher content of water and ethanol. There is also a general increase in ignition delay. Again, this increase is higher for emulsions with higher water concentration. Hopefully, the outcomes of the present study will increase further interest in combustion characteristics modification of conventional aviation fuels by emulsification. In addition, the findings of the present study will provide experimental data which can be applied for future computational modeling of the combustion process of emulsified fuel.

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