Structural aspects of coaxial oxy-fuel flames

Oxy-fuel combustion has been proven to increase thermal efficiency and to h ave a potential for NOx emission reduction. The study of 25-kW turbulent di ffusion flames of natural gas with pure oxygen is undertaken on a coaxial b urner with quarl. The structural properties are analysed by imaging the ins tantaneous reaction zone by OH* chemiluminescence and measuring scalar and velocity profiles. The interaction between the flame front and the shear la yers present in the coaxial jets depends on the momentum ratio which dictat es the turbulent structure development. Flame length and NOx emission sensi tivity to air leaks in the combustion chamber are also investigated.