Effect of heating liquid kerosene on ignition characteristics in an internally staged combustor

The effects of kerosene temperature (Tf) and combustor relative air-pressure drop (Δp/p3) on lean ignition were investigated in an engineering-scale internally staged combustor equipped with a centrifugal pilot atomizer under normal inlet conditions. The kerosene temperature was varied from ambient to 430 K and Δp/p3 from 1.5% to 5.5%. At fixed Δp/p3 values, increasing Tf significantly reduced the lean ignition fuel-to-air ratio (LIFAR), with the most significant reductions observed at low Δp/p3 values. For example, at Δp/p3 = 1.5%, the LIFAR decreased from 0.024 (ambient) to 0.004 (430 K). A transition in the controlling mechanisms was observed at Tf ≈ 350 K: for Tf ≤ 350 K, increasing Δp/p3 further reduced the LIFAR while improvement in Tf-driven atomization dominated the ignition boundary; for Tf > 350 K, the LIFAR increased with Δp/p3, thus indicating that aerodynamic effects associated with higher Δp/p3 values became dominant. Notably, at Δp/p3 = 5.5%, the LIFAR stabilized at approximately 0.010 over the investigated Tf range, thus suggesting the limited additional benefit of kerosene heating at Δp/p3 values.