The Effect of Water Vapor on Radiative Counterflow Diffusion Flames

The chemical and physical effects of water vapor on the structure of counterflow diffusion flames is investigated both experimentally and theoretically. The experimental flame structure measurements consist of profiles of temperature which are used for computation with detailed C2 chemistry. This enables describing the flame radiative heat losses more accurately. The flame structure results show that OH radical concentration increases as the water vapor concentration is increased. This increases the flame temperature and the CO2 production rate and decreases the CO production rate. Additional computations performed for strained radiative counterflow diffusion flames with and without gas radiation show that at low strain rate, gas radiation is important for reducing the peak flame temperature, while it has a negligible effect at high strain rates. Increase in water vapor substitution increases the radiation effect of the water inside the flame at low strain rates.