Droplet combustion in the presence of acoustic excitation

Acoustically Coupled Combustion of Liquid Fuel Droplets

“…2 Transactions of the ASME presence of soot in JP-8 and FT fuels is one of several differences between these fuels and alcohols; sooting is visible in these images due to the nature of the filters employed here [20,46]. Representative comparisons of average burning rate constants extracted from experiments involving nonfed (Eq.…”

“…Recent droplet combustion experiments by our research group at UCLA, involving the continuous delivery of fuel to the droplet via a fine capillary in either microgravity [43] or normal gravity [20], enable studies to be conducted over a longer period of time, on the order of minutes in normal gravity, with continual replenishment of the droplet and achievement of a quasi-steady droplet shape and size. This configuration is particularly useful in exploring the effects of acoustic coupling with the combustion process.…”

“…In normal gravity, quasi-steady burning and hence a relatively fixed droplet size can be achieved with a constant value of Q v delivered by a syringe pump [20], while in microgravity experiments (performed at NASA Glenn Research Center, Cleveland, OH), the need to rapidly grow and maintain a fixed droplet size in a 2-s time period necessitates the use of a closed loop controller with a controllable solenoid valve [43,44] to deliver fuel at variable rates, enabling formation of droplets of an appropriately fixed size. Most normal gravity experiments here involve fuel droplets with a diameter d eqvs of approximately 1-1.2 mm, while microgravity experiments involved droplets with a slightly larger diameter, in the range 1.3-1.6 mm.…”

“…Average K values are consistent with those quantified in others' experiments via a suspended nonfed droplet method and Eq. (2), for both microgravity studies and normal gravity experiments for the range of hydrocarbon fuels considered in Sevilla-Esparza et al [20]. These latter studies explore alcohol fuels (ethanol, methanol) as well as JP-8 and FT fuel, the latter being of special interest as an alternative transportation fuel [45].…”

“…(3). Temporally variable values of d eqvs are extracted from either video imaging [43] or phase-locked OH* chemiluminescence imaging for which droplets are backlit [20], in either case making the droplet interface quantifiable via edge detection software. Details on the procedures associated with this evaluation may be found in these references.…”