Dynamics Analysis of a Jet-Fuel Surrogate and Development of a Skeletal Mechanism for Computational Fluid Dynamic Applications

Abstract

The autoignition dynamics of a three component surrogate jet fuel (66.2% n-dodecane, 15.8% n-proplylbenzene, 18.0% 1,3,5,trimethylcyclohexane) suitable for usage as Jet A-1 and RP-3 aviation fuels are analyzed, using the detailed mechanism of Liu et al. (Liu et al. 2019). The conditions considered are relevant to the operation of gas turbines and the analysis is performed using mathematical tools of the computational singular perturbation (CSP) method. The key chemical pathways and species are identified in the analysis of a homogeneous adiabatic and constant pressure ignition system for a wide range of initial conditions. In particular, the key role of hydrogen and CO-related chemistry is highlighted, with an increasing importance as the initial temperature increases. The C 2 H 4 →C 2 H 3 →CH 2 CHO pathway is also identified to play a secondary but non-negligible role with an importance increasing with initial temperature, favoring the system's explosive dynamics and, thus, promoting ignition. Finally, C 2 H 4 is identified to be a species with a key (secondary) role to the system's explosive dynamics but its role is replaced by C 3 H 6 and eventually by O 2 , as the initial temperature increases. In the second part of the current work, a 58-species skeletal mechanism is generated using a previously developed algorithmic process based on CSP. The developed skeletal was tested in a wide range of initial conditions, including both ignition delay time 1Sharmin, August 5, 2020 and laminar flame speed calculations. For the conditions that were of interest in the current work, the skeletal approximated the detailed mechanism with very small error. The 58-species skeletal is shown to be ideal for use in CFD applications not only because of its small size but also because of its sufficiently slow associated fast timescale.

The chemical dynamics of hydrogen/hydrogen peroxide blends diluted with steam at compression ignition relevant conditions

“…(i) the development of simplified (skeletal) chemical kinetics mechanisms [157][158][159] (ii) the characterization of ignition phenomena [160][161][162] and the (iii) determination of the importance of chemical/transport processes for both major species and radicals [163,164]. In the current work it will be used to identify the important reactions related to NO and N 2 O.…”

Computational analysis of the effect of hydrogen peroxide addition on premixed laminar hydrogen/air flames

“…Interested in leading order accuracy, the CSP basis vectors a i , b i can be approximated by the right (α i ) and left (β i ), respectively, eigenvectors of the Jacobian J of g(z) [31,34,[48][49][50]. Apart from an amplitude, each CSP mode is described by a timescale which is defined as the inverse norm of the associated eigenvalue, i.e., τ i = |λ i | −1 , where [51][52][53]. A CSP mode is characterised as explosive if the associated eigenvalue is positive and dissipative otherwise [50].…”

Asymptotic Analysis of Detonation Development at SI Engine Conditions Using Computational Singular Perturbation

“…Then, the i-th timescale τ i can be calculated on the basis of the respective eigenvalue λ i , i.e., τ i = 1 |λ i | . The sign of the eigenvalue (positive or negative) determines the nature of the respective CSP mode; a negative eigenvalue indicates a dissipative mode that tends to drive the system towards equilibrium, while a positive eigenvalue is called explosive [2,93,94] that drives the system away from the equilibrium. Explosive modes have been extensively investigated in reacting flows because they are inherently related to limit phenomena and flames [95][96][97].…”