A tangent linear approximation of the ignition delay time. II: Sensitivity to thermochemical parameters

The tangent linear approximation (TLA) developed in Almohammadi et al. (Combust. Flame 230, 111426) is extended to estimate the sensitivity of the ignition delay time with respect to species enthalpies and entropies. The proposed method relies on integrating the linearized system of equations govern...

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Bibliographic Details
Published in:Combustion and flame 2022-01, Vol.235, p.111677, Article 111677
Main Authors: Hantouche, Mireille, Almohammadi, Saja, Le Maître, Olivier P., Knio, Omar M.
Format: Article
Language:English
Subjects:
Applications
Approximation
Butanol
Delay time
Engineering Sciences
Enthalpy
Estimates
Finite difference method
Gas mixtures
Ignition
Isooctane
Jacobian
Linearization
Local sensitivity
Mathematical Physics
Octane
Parameter sensitivity
Physics
Reactive fluid environment
State vectors
Statistics
Tangent linear approximation
Thermophysical parameter
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Summary:The tangent linear approximation (TLA) developed in Almohammadi et al. (Combust. Flame 230, 111426) is extended to estimate the sensitivity of the ignition delay time with respect to species enthalpies and entropies. The proposed method relies on integrating the linearized system of equations governing the evolution of the state vector’s partial derivatives with respect to variations in thermodynamic parameters. The sensitivity of the ignition delay time is estimated through a linearized approximation of a temperature functional. The TLA approach is applied to three gas mixtures, H2, n-butanol, and iso-octane, reacting in air under adiabatic, constant-volume conditions. The numerical experiments indicate that the linearized approximation of the ignition delay time’s sensitivity is in excellent agreement with the finite-difference estimates. This is also the case for sensitivity estimates obtained using the TLA approach. Further, significant computational speed-ups are achieved with the TLA approach, and the method scales well with the number of perturbed parameters. In the case of the H2 mechanism, TLA is about ten times faster than finite differences, and this enhancement becomes even more substantial when more complex mechanisms are considered.
ISSN:0010-2180
1556-2921
DOI:10.1016/j.combustflame.2021.111677