Impact of fuel properties on combusting jet fuel spray breakup, analyzed using high-speed phase contrast imaging

High-speed x-ray phase contrast imaging of combusting jet fuel spray in a single-sector, swirl stabilized combustor is conducted using the high-powered x-ray source at Argonne National Laboratory’s Advanced Photon Source. Imaging is conducted at 90,517 Hz on four fuels which span a wide range of combustion-relevant properties, including F-24, C-1, C-3, and C-5 fuels. F-24 is the standard jet fuel used by the U.S. Department of Defense, and the category C fuels are alternative blends that were created as part of the National Jet Fuel Combustion Program, which each demonstrate one or more extreme properties. The fuel spray breakup of these different fuels is investigated qualitatively by comparing differences between phase-contrast images collected at the same conditions on different fuels. An image processing routine is subsequently used to extract quantitative droplet information, including diameter and velocity, from the collected images. This allows detailed study on the effects of fuel properties on jet fuel spray breakup and atomization. These results demonstrate that droplet characteristics vary significantly between the four tested fuels and that fuels that are more volatile tend to lead to smaller droplets with higher velocities. Phase contrast imaging is found to be extremely effective at characterizing ligaments and droplets inside of an operating gas turbine combustor. This technique shows great promise for providing detailed spray boundary conditions for future gas turbine combustor simulations.