衝突噴流場に形成された乱流予混合火炎および乱流非予混合火炎の構造とNO_x排出特性  [in Japanese] Structure and NO_x Formation Characteristics of Turbulent Premixed Flame and Turbulent Nonpremixed Flame Produced by Opposed Jet Burner  [in Japanese]

Turbulent nonpremixed (diffusion) flames are employed in many industrial burners or practical combustors, because they are stable over a wide range of turn-down ratio. With currently increasing concern for pollutant emissions, these flames have become unamenable because in general the combustion process is difficult to be controlled to reduce emissions of NO_x and soot. In the present study, turbulent nonpremixed flame was produced in a highly turbulent flow field achieved by an opposed jet burner. It was found that with gas sampling technique, emission characteristics and mixture fraction profiles of this flame were same as those of the premixed flame due to rapid mixing of fuel and air. This fact suggests that the opposed jet combustion reduces the pollutant emission from Diesel engines and gas turbines.