Effects of pool diameter and oxygen concentration on combustion and heat-feedback characteristics of rocket-kerosene pool fires

Parallel loading of liquid oxygen and rocket kerosene can produce simultaneous leaks and oxygen-enriched atmospheres at launch sites, intensifying liquid-fuel pool-fire hazards. In this study, rocket-kerosene pool fires were experimentally investigated in a vertical low-velocity wind tunnel at oxygen concentrations of 21–100% and pool diameters of 1–5 cm. The mass-loss rate, flame morphology, pulsation frequency, plume axis temperature, and radiative heat flux were measured to clarify the effects of oxygen concentration and pool diameter on combustion enhancement and heat-feedback transition. Oxygen enrichment accelerated fuel heating and evaporation, advanced boiling-enhanced burning, and greatly increased mass-loss and heat-release rates, especially in small pools. Flames became taller, wider, brighter, and more pulsating. Under pure oxygen, peak radiative heat flux rose by factors of 4–47. Maximum plume-axis temperatures increased from 567 °C to 1007 °C for the 2 cm pool and from 607 °C to 1125 °C for the 4 cm pool. Heat-feedback analysis showed a shift from convection-dominated burning in air to radiation-dominated feedback in several oxygen-enriched small-pool cases, with large-pool behavior governed by optical-thickness effects. Modified flame correlations and a two-scale transition model provide predictive tools for launch-site thermal-risk assessment.