Combustion characteristics and entrainment behavior of rectangular jet flame in cross airflow

Fossil fuel combustion is widely employed in the discharge process of exhaust gases from industrial torch to prevent the explosion accidents and environment pollution, which is of vital importance to efficient utilization and conversion of energy. This paper investigated experimentally the combustion dynamics and entrainment of rectangular buoyant jet flame in cross airflow, which has not been quantified comprehensively. Four rectangular burners with same exit area and different aspect ratio were used in the experiments with a series of fuel mass flow rates (heat release rates) and airflow speed. The long side (Case 1) or the short side (Case 2) of the burner is perpendicular to the direction of cross airflow. Dimensional analysis of the flame development and physical model were developed in view of the jet momentum and flame driving buoyancy, which determine a characteristic length scale and volumetric flow rate to formulate the flame profile. Meanwhile, an integral model involving of mass and momentum conservation equations was derived to analyze the experimental results. When the aspect ratio n is from 1:1 to 71:1, the entrainment coefficient increases from 0.037 to 0.044 for case 1, while decreases from 0.037 to 0.028 for case 2. The effective entrainment coefficients of Case 1 are a little larger than Case 2 showing a stronger entrainment effect caused by the long side, which provides a new insight to energy combustion in airflow.