Abstract:

In order to reduce the probability of fire accidents in coal mine pipelines and explore ways to inhibit the acceleration of flames that trigger disasters, the main characteristics of flame development and acceleration within the pipeline were analyzed. The algebraic second-order moment-probability density function-based turbulent combustion model was sought to build a theoretical model that describes the development and acceleration of a turbulent flame in a tube. Numerical simulations were adopted to study the development and acceleration of flames induced by methane and air mixture in a combustion tube with one end closed and the other open. The results show that in the center line of the tube, the flame surface with higher gradients of gas temperature and gradient of fuel concentration is the reaction zone, and the averaged turbulence reaction rate is higher; there is a jump in the gas axial velocity in the reaction zone, and at the same time, a peak in the turbulent kinetic energy distribution appears; the averaged gas reaction rate is affected by turbulence; the gradual increase in turbulence in the reaction zone leads to the gradual expansion of the reaction zone, thereby promoting the acceleration of the flame.

Key words: turbulent flame, flame development, flame acceleration, combustion tube, premixed gas