A Comparative Study of the Detonation Chemistry and Critical Detonation Parameters for Jet A and a Bio-derived Jet Fuel

Abstract The use of conventional jet fuels in detonation-based engines is emerging as a promising possibility due to the risks associated with the use of hydrogen as a fuel for commercial aviation. The development of liquid-fueled detonation engines heavily depends on the basic understanding of the...
Ausführliche Beschreibung

Abstract The use of conventional jet fuels in detonation-based engines is emerging as a promising possibility due to the risks associated with the use of hydrogen as a fuel for commercial aviation. The development of liquid-fueled detonation engines heavily depends on the basic understanding of the detonation chemistry and the combustion behavior of these real fuels in a detonating environment. The current work presents a systematic study of the detonating behavior of two real fuels. The fuels studied are Jet A, a conventional jet fuel used in the aviation industry, and a synthetically developed bio-derived jet fuel, C1. 1D ZND computations are used to compute the relevant detonation properties. The high-temperature chemistry of Jet A and C1 is modeled using a HyChem chemical kinetics model. The detonation chemistry of real distillate fuels was investigated in this study numerically, where relevant chemical length and time scales were calculated and compared. The critical detonation parameters were also evaluated and compared over a range of initial conditions and equivalence ratios. The detonability limits of real distillate fuels were investigated for their application in detonation-based combustors. The fuel–air–diluent mixtures were also studied in the present work, with argon and helium as inert diluents. The ZND computations show that the induction length scale for Jet A–air detonations is nearly half when compared to that of C1–air detonations which can be attributed to the detonation chemistry of the two fuels considered here. The major difference between the detonation chemistry of Jet A and C1 is a result of the composition of major pyrolysis products. The major decomposition product for Jet A is ethylene ($ C_{2} %$ H_{4} $); whereas, for C1, it is iso-butene (i-$ C_{4} %$ H_{8} $). The larger molecular weight of iso-butene leads to smaller diffusivity which results in larger detonation length and time scales for C1 when compared to Jet A at the same initial conditions. The primary objective of the present study is to show how fuel chemistry plays a crucial role in the detonation phenomenon. The study also highlights the effect of fuel composition and their pyrolysis products on the detonating behavior of real fuels for their application in detonation-based engines. Ausführliche Beschreibung