Single droplet ignition and combustion of Jet-A1, vegetable oil and their blends in a drop tube furnace

The aeronautical sector needs to introduce alternative fuels in order to achieve a reduction in greenhouse gas emissions. A possible solution in the near future might be the blending of biofuels with jet fuel, which would allow the use of a greener fuel without significant changes in the existing fleets of the companies, which means the development of a “drop in” fuel. The present work aims to study the ignition and combustion characteristics of single droplets of jet-A1 (JF), hydroprocessed vegetable oil (NExBTL) and their mixtures in a drop tube furnace (DTF). The droplets were injected into the DTF using a droplet generator. Experiments were conducted in air for three DTF wall temperatures (900, 1000 and 1100 ºC). The ignition and combustion of the droplets were evaluated through the images obtained with a high-speed camera coupled with a high magnification lens. The images allowed for the observation of the burning phenomena, and data are reported for temporal evolution of droplet sizes and burning rates. The results revealed that the mixtures followed the 2 law, except the mixture with 75% JF for a DTF wall temperature of 1100 ºC. This was due to the occurrence of puffing, which enhanced the burning rates. In addition, it was observed that the mixtures with higher content of JF present brighter flames, and higher burning rates.Fundação para a Ciência e a Tecnologia