Mathematical Investigation of Oscillating Flame in Non-Premixed Counterflow Combustion of Particles

In this research, the influence of various effective dimensionless numbers on initiation of instability in combustion of organic particles is evaluated. A non-premixed counterflow combustion is considered assuming a thin region of vaporization where lycopodium particles are assumed as the solid fuel particles. It is assumed that particles as fuel and air as oxidizer move toward stagnation plane from two nozzles in the counterflow configuration. Particles initially vaporize in order to release a specific chemical gas which then enters the oxidation reaction process. To investigate oscillating characteristics of flame, governing equations are rewritten in dimensionless space-time coordinates. By solving these equations and combining them, a new expression is obtained. Also, by solving this equation, it is possible to predict initiation of instability in organic dust flame. According to the obtained results, by increasing Lewis number, threshold of instability happens earlier. Increasing wave number causes the instability boundary to go higher. It is also concluded that at a constant wave number, by increasing Zeldovich number, the onset of pulsating instability could occur with a smaller Lewis number.