Numerical investigations on the flame propagation characteristics of hydrogen detonation

Numerical investigations are conducted to effectively analyze the propagation of premixed hydrogen air detonation in small-scaled L-shaped ducts. The initial burst pressure exhibits an important impact on the flame behavior. The higher the initial burst pressure, the higher the extremum pressures. The peak pressure in a fully closed duct is equal to the peak pressure in a semi-closed duct with the initial burst pressure three times higher. At the early stage of the burst, pressure instabilities generate temperature instabilities. Due to the thermal-diffusive effect, the arc-shaped flame front becomes the planar flame front within 5μs. At the corner of the L‐shaped ducts, pressure difference creates a vortex, which separates the interaction between the flame front and the unburned gas, and leads to the formation of a tilted flame front. The pressure difference on the cross-section plane of the ducts triggers the velocity difference, and there is flame acceleration up to Mach 2. The corner generates multiple reflections of the pressure wave, and thus, the high-temperature zone can be self-sustained.