Investigation on spray combustion characteristics of Boron-Loaded slurry fuel in a Swirl-Stabilized combustor

For many decades, liquid hydrocarbon fuels are being used to propel air-breathing engines. However, the energy content of liquid hydrocarbon fuels has reached close to its limitation. Any further improvement in energy value is quite difficult through chemical methods. Slurry fuels, which are colloidal suspensions of solid energetic particles in liquid fuel, became a potential alternative fuel. Among several solid additives, boron is considered the best choice because of its higher heating values. However, our knowledge about boron-loaded slurry fuel is very limited. Therefore, here in this study, we experimentally investigated the combustion characteristics of boron/Jet A-1 slurry fuel spray in a swirl-stabilized combustor. A particle loading of 10% by weight is considered here for the experiment. The feed boron, as well as the burnt boron samples, were characterized using standard material characterization techniques in order to understand the surface morphology, oxidation behavior, and active boron content. The combustion characteristics of slurry fuel were analyzed through spectroscopy and BO2* chemiluminescence imaging. Positive thermal contribution from boron combustion was quantified via temperature measurements at three different radial locations of the combustor exit. The spectroscopy and chemiluminescence signatures indicate that combustion of boron particles occurs downstream of the dump plane. The exit temperature of boron-laden slurry fuel measured at all three different radial locations is higher compared to neat Jet A-1. An increment of 19% in exit temperature was observed in the case of boron slurry fuel relative to neat Jet A-1. The X-ray diffractograms (XRD) and thermogravimetric analysis (TGA) show the complete oxidation of boron particles.