Propagation characteristics of C2H4/air detonation waves affected by a weakly confined air layer containing water mist

This study examines the effects of a weakly confined air layer containing water mist on C2H4/air detonation wave propagation and investigates how the gas-phase temperature in the confined layer influences detonation dynamics. Results show that the dominant mechanism is heat absorption during water mist vaporization, which reduces detonation intensity and alters post-detonation temperature distribution. Compared to pure air confinement, mist-containing layers cause faster detonation extinction. This occurs because droplet evaporation cools combustion products behind the wave, weakening the leading shock and suppressing the generation of new downward transverse waves upon shock–interface interaction, thereby disrupting detonation sustainability. Increasing the confined layer's temperature mitigates thermal losses. Concurrently, modified oblique shock structures enhance transverse wave formation at the front, extending propagation distance and enabling self-sustained propagation. During lateral expansion, droplets near the confined interface rapidly evaporate, absorbing heat and forming a low-temperature zone behind the contact surface. Droplets farther from the interface, in cooler regions near the contact surface, evaporate slowly and are instead convected into a dense droplet cluster by combustion products. Higher confined layer temperatures reduce acoustic impedance, enhancing lateral diffusion of combustion products, increasing their penetration depth, and forming a wider low-temperature zone. When the temperature reaches high levels (e.g., 1000 K), water mist vaporization intensifies significantly, expanding the low-temperature region, further lowering its minimum temperature, and increasing gaseous water concentration. These findings highlight the critical coupling between droplet-phase heat transfer and shock dynamics in weakly confined detonation environments.