Blowout Characteristics of Partially Premixed Flames of Prevaporized Blends of Biofuels and Petroleum Fuels

Abstract

The laminar partially premixed flames of prevaporized Jet-A, canola methyl ester (CME) and blend flames of Jet-A and CME were studied over a range of equivalence ratios of 0.6–0.8 with and without heated coflow. Measurements of blowout velocities and flame temperature profiles were made. The injector was designed to produce a uniform inner flow and had an inner diameter of 12.7 mm. The flames were laminar and blue in color (dominated by homogeneous gas-phase reactions). The temperature profiles in all the flames were similar, with a peak temperature of 1680 K. The blowout velocity increased with equivalence ratio for all the flames; the blowout velocity of pure CME flames was higher than that of pure Jet-A flames with no coflow present. The blowout velocity of the blend flames ranged around the values for the pure fuel flames. A Damkohler number (based on the velocity gradient at the jet boundary and chemical reaction time scale estimated from laminar flame velocity) of unity characterizes the blowout velocity. As the coflow velocity was increased, the blowout velocity was increased, and the differences between the values for the various flames became smaller.