Effect of Nanosecond Plasma Preconditioning on Detonation in High-Pressure H₂/O₂ Mixtures: A Multiscale Numerical Study

Abstract This work investigates the effect of nanosecond-plasma preconditioning on detonation in high-pressure hydrogen-oxygen mixtures through a multiscale numerical framework coupling zero-dimensional plasma kinetics, one-dimensional ZND detonation analysis, and two-dimensional reactive CFD. ChemPlasKin is used to compute the post-discharge thermochemical state of hydrogen oxygen mixtures, which is then mapped at the end of the afterglow as the initial condition for both ZND and CFD calculations. Parametric analyses are performed at 10 bar over reduced electric field (140–260 Td), deposited energy (25–150 mJ/cm 3 ), and equivalence ratio (0.2–1.2). The ZND results show that non-equilibrium plasma discharge has little effect under lean conditions, whereas for ϕ ≥0.8 it shortens the induction length and reduces the predicted detonation cell size by up to 30%. In addition, the threshold reduced electric field required to produce a measurable plasma effect increases by approximately 40 Td for every 0.4 decrease in equivalence ratio. A complementary multi-pulse analysis shows that pulse repetition is effective mainly when the deposited energy per pulse is kept constant, while redistributing the same total energy over a larger number of weaker pulses yields only a limited additional benefit. The sensitivity analysis shows that the dominant control of detonation cell size remains associated with the main hydrogen branching reaction H + O2 ≤>O + OH in both clean and plasma-treated mixtures. At higher pulse energy, the sensitivity pattern changes markedly, with the HO 2 /H 2 O 2 submechanism becoming significantly more influential. Two-dimensional DDT simulations in a 0.9 mm channel confirm that these thermochemical modifications strongly accelerate the transition, reducing the run-up distance and onset time from 68.5 mm and 136 μs in the untreated case to 9.7 mm and 17.5 μs in the most activated configuration. Overall, the results show that nanosecond plasma preconditioning can substantially compress detonation scales and promote faster DDT for high-pressure hydrogen-oxygen microdevices.