Atomization and combustion of a gelled, metallized slurry fuel

Two commercially available atomizers were tested for their ability to atomize a gelled boron slurry fuel. Particle size distributions were measured in non-reacting flow using a Malvern 2600 HSD Laser Diffraction Particle Sizer. A sub-scale ramjet combustor was designed and fabricated which utilized a sudden expansion inlet dump together with inlet air swirl for flame stabilization. An airblast atomizer produced sufficiently small particles for good combustion, but at the cost of a high pressure drop across the atomizer, making it impractical for use in a slurry fueled ramjet. Sustained steady combustion of the slurry fuel was not achieved using the airblast atomizer. A whistle type ultrasonic atomizer also produced sufficiently small particles and at a much lower pressure drop across the atomizer. Sustained stable combustion was achieved using the ultrasonic atomizer which yielded a combustion efficiency of 76% at 96 psia and an equivalence ratio of 0.78.