Effects of thermal stressing on the turbulent flame speed of jet fuel

Gas turbine engines for propulsion applications can use fuel as a coolant, exposing the fuel to high temperatures well within the ranges associated with thermal decomposition. Species produced as a result of these processes have been shown to correlate with changes in the combustion performance of the fuels. In this study, jet-A was thermally stressed over a range of temperatures (300-500°C) and residence times (10-14 s). The thermally stressed fuel is subsequently cooled to 200°C, and burned in a premixed turbulent Bunsen burner. Measurements of the global turbulent consumption speed are used to evaluate changes in fuel performance caused by auto-oxidation and thermal cracking. The results show no measurable difference in the global turbulent consumption speed of jet-A when it is preheated to up to 500°C compared to unheated samples. This indicates that heating jet-A up to 500°C does not cause significant auto-oxidation and thermal cracking reactions in the fuel that would measurably alter its combustion characteristics.