During the reporting period, the project delivered coordinated theoretical, numerical, and experimental progress on hydrogen combustion under external electromagnetic fields and non-thermal plasma, following a multi-scale, multi-physics strategy from atomistic modelling to flame-scale solvers, DNS, and laboratory validation.
At the atomistic scale, reactive molecular dynamics was used to quantify electric-field effects on hydrogen combustion chemistry and to assess the role of charge equilibration. A systematic comparison of QEq-based methods, QTPIE, and the physically grounded ACKS2 scheme showed that commonly used approaches can produce unphysical long-range charge transfer and artificially enhanced reaction rates under applied fields. ACKS2 provided more realistic charge distributions and molecular neutrality, establishing methodological guidance for reliable MD studies and clarifying the physical interpretation of field effects.
At the kinetic/PAC scale, the zero-dimensional ChemPlasKin framework was analysed, validated, and improved to strengthen the coupling between electron kinetics and combustion chemistry. Validation against literature H2/O2 cases confirmed correct prediction of ignition delay, radical production, and electron-driven excitation. Numerical robustness was improved by introducing measures to avoid instabilities and unphysical overheating (including extended post-ignition integration and improved energy-deposition control), and a sensitivity study on EEDF update criteria identified key controlling parameters.
A 1D steady-state plasma-assisted flame solver (PlasmaStFlow) was developed by extending Cantera’s StFlow formulation. The solver couples detailed combustion chemistry with non-equilibrium plasma kinetics via a Boltzmann solver to compute electron-impact reactions and plasma energy deposition self-consistently. It was validated in no-plasma conditions with excellent agreement against standard Cantera solutions. Initial plasma-activated simulations reproduced expected trends but revealed stiffness at high reduced electric fields, motivating targeted developments such as adaptive continuation and localized field activation. The main outcome is a functional, physically consistent 1D PAC tool that bridges plasma kinetics and flame-scale modelling and provides a pathway toward CFD-compatible reduced models.
On the experimental side, a dedicated platform was established to study electromagnetic interactions in premixed laminar hydrogen flames, including a burner and electrode configuration optimized via electrostatic simulations. The setup enables static and time-modulated electric fields combined with acoustic forcing. Flame response was measured using velocity diagnostics and OH* chemiluminescence, allowing the derivation of Flame Transfer Functions (FTF) and Flame Describing Functions (FDF). First results quantified the sensitivity of gain and phase to forcing amplitude, providing a baseline for future electro-acoustic coupling studies and model validation.
At the turbulence-resolving scale, a multi-physics DNS framework was extended to include electromagnetic body forces and magnetic-field effects in reacting-flow solvers. Governing equations and force models were implemented and verified, and code optimisations reduced computational cost without compromising accuracy. Initial simulations produced detailed fields of electromagnetic forcing and its interaction with flame structure, generating high-fidelity datasets to inform reduced modelling.
Finally, complementary work investigated nanosecond repetitively pulsed (NRP) discharges in hydrogen-reactive environments. High-resolution fluid simulations of streamers under temperature and density gradients representative of flames quantified acceleration, energy-deposition patterns, and discharge–flame interactions. These results provide physically consistent inputs and datasets for phenomenological plasma models and for future LES/RANS implementations of plasma-assisted combustion.
