Numerical simulation study and dimensional analysis of hydrogen explosion characteristics in a closed rectangular duct with obstacles

The influence of obstacles on hydrogen explosion is studied by numerical simulation and dimensional analysis. The numerical simulation is conducted based on the premixed model in a closed rectangular duct with rectangular obstacles, and ten variables that affect the flame propagation velocity are analyzed by dimensional analysis. Continuous acceleration of flame and collision annihilation of flame were successfully realized through triangular obstacles in simulation. The result shows that with the number of obstacles changes, the flame invariably converts to hemispherical flame, finger flame, tongue flame, quasi-plane flame, and mouth flame in turn. But the flame front is more twisted in two obstacles due to hydrodynamic instability and vortices. Through the comparative analysis of the flame and flow field in the duct during hydrogen explosion. It is found that the flame-obstacles-flow field coupling and its hydrodynamic phenomena determine the flame deformation and changes in propagation velocity. The result of the dimensional analysis shows that the drag coefficient can well depict the effects of the shape of the obstacles, and the dimensionless qualitative and quantitative model of flame propagation speed is given and verified.