Experimental investigations on the stabilization of lifted kerosene spray flames with coflow air

Abstract

ABSTRACTIn the present work, detailed experimental investigations have been carried out to understand the effect of coflow air on the stabilization of lifted spray flames with kerosene fuel. Two full cone type pressure swirl nozzles N1 and N2 ( = 1.7 and 7.08 kg/h at ΔPinj = 9 bar) are considered for experiments with a moderate fuel injection pressure range (4–12 bar). The flame liftoff height is observed to increase with fuel injection pressure for lower coflow velocity range (≤ 0.2 m/s). At higher coflow velocities (0.2–0.4 m/s), the flame liftoff height decreases with an increase in fuel injection pressure. At lower injection pressures, the flame liftoff height has been observed to increase significantly for higher coflow velocities. Detailed droplet velocity measurements using PIV and droplet size measurement using the shadowgraphy technique in cold flow helped understand the stabilization of lifted spray flames in the domain. At higher coflow velocities and lower injection pressure, smaller droplet number density allows additional air entrainment and flame stabilizes at the downstream location, where SMD and droplet flow velocities are small. At higher injection pressure, high droplet number density reduces the additional air entrainment, which stabilizes lifted spray flame at a relatively downstream location. At lower coflow velocity and lower injection pressure, flame stabilizes upstream, where mixture burning velocity is nearly equal to flow velocity irrespective of higher SMD and droplet flow velocity. At higher injection pressure, flame stabilizes only after the end of high velocity zones, as observed from PIV measurements.