A Comparative Study of Critical Detonation Parameters for Jet A and an Alcohol-to-Jet Synthetic Biofuel
Ashlesh Dahake, Ajay V. Singh
Abstract
View Video Presentation: https://doi.org/10.2514/6.2022-0819.vid The use of jet fuels in detonation-based engines is emerging as a promising possibility due to the risks associated with using 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 detonating behavior of these real fuels in the harsh environments of detonation combustion. 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 biofuel, 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 detonation is nearly half when compared to that of C1-air detonation. The major difference between the detonation chemistry of Jet A and C1 is the major pyrolysis product. The major decomposition product for Jet-A is ethylene (C2H4), whereas, for C1, it is iso-butene (i-C4H8). The larger molecular weight of iso-butene leads to smaller diffusivity and thus larger length and time scales for C1 as compared to Jet-A. The fundamental objective of this article is to show how fuel chemistry plays a role in the detonation phenomenon and highlight the effect of foundational fuel composition on the detonating behavior of real fuels for their application in detonation-based engines