Pollutants emission in the counterflow diffusion flame

The development of new ways of fuel incineration with the purpose of reduction of the pollutants emission is the one of priority directions in energetics. At present work the numerical investigation of the new scheme of fuel incineration in the counterflow diffusion flames is carried out, Two variants of the fuel feed are considered: a pure fuel and a premixed fuel-oxidizer mixture with the fuel contents more than stoichiometric, The one-step and multi-step fuel-oxidizer chemical reactions are considered. A structure of the counterflow diffusion flame for a wide range of the values of the flame strain rate and initial species concentrations is investigated. It is shown that in the case, when the fuel is fed as a premixed mixture with oxidizer, the two regimes of counterflow combustion are possible. The first regime does not practically differ from ordinary counterflow combustion with a single reaction zone. The structure of a flame for the second regime is more complex and contains two reaction zones. The first reaction zone is similar to premixed diffusion flame in the fresh fuel-oxidizer mixture, and the second reaction zone corresponds counterflow diffusion flame in oxidizer and reaction products, formed in the primary premixed flame, Parametrical research of effect of a flame strain rate on the structure of a diffusion flame and combustion products emission is carried out. The fuel-air partial premixed counterflow diffusion flame is discussed, It is shown, that the existence of two reaction zone in this diffusion flame allows to separate the two general stages of fuel-air chemical reaction and to control the process rate and pollutants emission.