Dissertation Defence: Influence of Atomization on Single and Multi-Droplet Combustion
April 16 at 9:00 am - 1:00 pm
Sepehr Mosadegh, supervised by Dr. Sina Kheirkhah, will defend their dissertation titled “Influence of Atomization on Single and Multi-Droplet Combustion” in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Mechanical Engineering.
An abstract for Sepehr Mosadegh’s dissertation is included below.
Examinations are open to all members of the campus community as well as the general public. Registration is not required for in person exams.
The global energy supply will rely on liquid fuels in the foreseeable future, with diesel-like variants witnessing the highest demand across various industries. Recent initiatives have focused on renewable biofuels such as biodiesel and ethanol, which are emerging as environmentally friendly alternatives to conventional diesel. Concurrently, incorporating nanomaterials, specifically Graphene Oxide (GO), into liquid fuels has demonstrated substantial enhancements in combustion power and emission characteristics. In the context of blended and doped fuels, atomization processes involving nucleation, expulsion, and droplet ejection play important roles, potentially influencing combustion characteristics. The focus of the present dissertation is quantifying the effects of atomization on burning rate, dynamics, and flame spread for single and multi-droplets. Suspensions of GO with doping concentrations of 0–0.1\% in diesel, biodiesel, and ethanol, were prepared, and characterized.
Results of experiments concerning ethanol doped with GO show consistent characteristics of ejected baby droplets for several test conditions. The results suggest the possible burning of the baby droplets within the flame envelop. A conservation-of-mass framework is used and it is shown that after droplets atomize, burning rate increases, but the rate of evaporation decreases. For ethanol droplets, GO addition and increased doping concentration improve the overall burning rate. In GO-doped diesel fuels, atomization induces a low-frequency intermittent coupling between the droplet size and flame chemiluminescence intensity, with amplified oscillations observed at higher GO concentrations. Such low-frequency oscillations are also observed for single and multi-droplet combustion of biodiesel blended with ethanol and doped with GO. For multi-droplet combustion, despite minimal impact on flame dynamics and spread rate among neighboring droplets, the addition of GO introduces a new mode of flame spread. Compared to doping with GO, blending of biodiesel with ethanol leads to significant increase of the flame spread rate due to intensified atomizations. The results presented in this thesis provides valuable insights into the intricate dynamics of atomization, combustion, and flame spread between atomizing droplets.