Experimental study of N$_2$ dilution on bluff-body stabilized LPG jet diffusion flame

The present paper reports the effects of N$_2$ addition and preheating of reactants on bluff-body stabilized coaxial LPG jet diffusion flame for two cases, namely, (I) preheated air and (II) preheated air and fuel. Experimental results confirm that N$_2$ addition to the fuel stream leads to an enhancement in flame length, which may be attributed to the reduction in flame temperature. The soot free length fraction (SFLF) also increases, which might be caused by the decrease in fuel concentration and flame temperature. The flame length and also the SFLF are observed to be reduced with increasing temperature of reactants and lip thickness of the bluff body. The NO$_x$ emission level for all burner configurations are found to be attenuated with nitrogen addition, which can be attributed to the reduction of the residence time of the gas mixture in the flame. The emission index of NO$_x$ (EINO$_x$) also becomes enhanced with increasing lip thickness and reactant temperature due to an increased residence time and thermal effect, respectively.