A generalised virtual chemistry formalism with standardised thermodynamics, kinetics and complex transport properties

Accurately and efficiently modelling combustion remains a central challenge in the transition to low-carbon energy systems. Virtual chemistry has emerged as a powerful chemistry reduction strategy, relying on optimised species and reactions to reproduce reference flame behaviours at a fraction of the computational cost. However, previous formulations depend on tabulated parameters, limiting their extrapolation capabilities and integration into standard reactive flow solvers. To address these limitations, a new standardised virtual chemistry formalism has been introduced, bridging virtual and detailed chemistry through chemical equilibrium between real and virtual species. The present work extends the framework to accurately capture laminar flame structures by jointly optimising the thermodynamic, kinetic and transport properties. Special attention is given to validating and generalising virtual mechanism structures, with the development of a novel architecture dedicated to pyrolysing fuels and multi-component fuel surrogates. The resulting highly-reduced optimised mechanisms adopt architectures compatible with CHEMKIN and CANTERA solvers. The methodology is applied to representative decarbonised and conventional fuels: Hydrogen, Dodecane, which is a key component of Sustainable Aviation Fuels (SAFs), a multi-component SAF surrogate and a Jet A multi-component surrogate. Particular emphasis is placed on reproducing flame structures across a wide range of combustion regimes, including premixed and non-premixed, adiabatic and non-adiabatic conditions. The results demonstrate the ability of the proposed virtual mechanisms to replicate reference flame structures with drastically reduced complexity, chemical stiffness and CPU time, paving the way for straightforward and efficient high-fidelity combustion simulations.