A tangent linear approximation of the ignition delay time. I: Sensitivity to rate parameters

• Published in: Combustion and flame Vol. 230; p. 111426
• Main Authors: Almohammadi, Saja, Hantouche, Mireille, Le Maître, Olivier P., Knio, Omar M.
• Format: Journal Article
• Language: English
• Published: New York Elsevier Inc 01-08-2021; Elsevier BV; Elsevier
• Subjects: Approximation; Delay time; Engineering Sciences; Finite difference method; Gas mixtures; Ignition; Independent variables; Jacobian; Linearization; Local sensitivity; Mathematical Physics; Parameter sensitivity; Perturbation; Physics; Random variables; Rate coefficients; Reaction mechanisms; Reactive fluid environment; State vectors; Tangent linear approximation; Uncertainty; Uncertainty factor; Uncertainty factor; Local sensitivity; Jacobian; Rate coefficients; Tangent linear approximation; rate coefficients; local sensitivity; uncertainty factor; tangent linear approximation
• ISSN: 0010-2180; 1556-2921
• DOI: 10.1016/j.combustflame.2021.111426

A tangent linear approximation is developed to estimate the sensitivity of the ignition delay time with respect to individual rate parameters in a detailed chemical mechanism. Attention is focused on a gas mixture reacting under adiabatic, constant-volume conditions. The uncertainty in the rates of elementary reactions is described in terms of uncertainty factors, and are parameterized using independent canonical random variables. The approach is based on integrating the linearized system of equations governing the evolution of the partial derivatives of the state vector with respect to individual random variables, and a linearized approximation is developed to relate the ignition delay sensitivity to the scaled partial derivatives of temperature. The efficiency of the approach is demonstrated through applications to chemical mechanisms of different sizes. In particular, the computations indicate that for detailed reaction mechanisms the TLA leads to robust local sensitivity predictions at a computational cost that is order-of-magnitude smaller than that incurred by finite-difference approaches based on one-at-a-time rate perturbations.