Experimental and numerical investigations on the laminar burning velocity of n-butanol + air mixtures at elevated temperatures

Abstract

Laminar burning velocities of n-butanol + air mixtures were measured experimentally at elevated mixture temperatures using an externally heated meso-scale channel configuration. The measurements were carried out at atmospheric pressure for an equivalence ratio range 0.7–1.3 and unburnt mixture temperature range of 350–600 K. Planar, stretch free and nearly adiabatic flames were stabilized in the diverging channel and used to extract the laminar burning velocity data based on mass conservation between the channel inlet and flame stabilization point. A skeletal kinetic-mechanism (124 species and 943 reactions) based on a previous model of Sarathy (2014) was developed to compare the present experimental results with mechanism predictions. Besides the skeletal model predictions, n-butanol experimental results were also compared with other recent kinetic models reported in literature. The effect of unburnt mixture temperature on burning velocity of n-butanol + air mixtures was evaluated using the power-law correlation: Su=Su,0Tu/Tu,0α. The variation of temperature exponent (α) with equivalence ratio (Φ) was reported also for the first time. The values exhibit a non-linear inverted parabolic profile with a minimum value occurring for slightly rich mixtures at Φ = 1.1.