Mild combustion is considered as a promising combustion technology for energy saving and low emission of
combustion product gases. In this paper, the controllability of reaction region in mild combustion is examined
by using co-axial air nozzle. For this purpose, numerical approach is carried out. Propane is considered for
fuel and air is considered for oxidizer and the temperature of air is assumed 900K slightly higher than auto
ignition temperature of propane. But unlike main air, the atmospheric condition of co-axial air is considered.
Various cases are conducted to verify the characteristics of Co-Axial air burner configuration. The use of coaxial
air can affect reaction region. These modification help the mixing between fuel and oxidizer. Then, reaction
region is reduced compare to normal burner configuration. The enhancement of main air momentum also
affects on temperature uniformity and reaction region. The eddy dissipation concept turbulence/chemistry interaction
model is used with two step of global chemical reaction model.