Numerical study on the propagation characteristics of detonation waves in a semi-confined straight channel with periodic longitudinal concentration gradients

Based on OpenFOAM simulations, this study investigates detonation wave propagation in a semi-confined channel filled with combustible mixtures exhibiting periodic longitudinal concentration gradients. The study focuses on the effects of gradient amplitude and period on propagation characteristics and underlying mechanisms. Results indicate that increased amplitude drives the development of irregular cellular structures, generates high-pressure zones, and induces localized overdriven detonation, enhancing transverse wave formation and sustaining propagation. Furthermore, higher amplitudes improve the effectiveness of reflected shocks, reduce energy dissipation, and extend the range of self-sustained propagation. In low-reactivity zones, elevated argon concentration increases mixture density, amplifying shock pressure, whereas fuel-rich regions intensify transverse wave strength. This synergistic interaction facilitates detonation re-initiation. Shorter periods generate compact fuel-rich zones and high-frequency transverse waves, boosting propagation stability, while longer periods suppress transverse wave formation and accelerate attenuation. These findings provide a theoretical basis for active control of detonations in non-uniform concentration fields.