Ignition of Aircraft Combustible Fluids by Hot Surface Under Ventilation

Abstract

Flight-fire is a crucial factor that affects the safety of aircraft. It mainly results from combustible fluid leakages on hot surfaces. Hence, this study investigates the ignition probability of a droplet on a hot surface under ventilation through experiments. Specifically, two types of widely used combustible fluids, No. 3 Jet Fuel and Mobile Jet Oil II, were investigated at varying surface temperatures ranging from 500 °C to 700 °C. This range covers the non-ignition to sure-ignition temperatures for the two fluids. The experiments were carried out considering the actual ventilation conditions of an aircraft, wherein the airflow rate ranged from 0 m/s to 3 m/s, and the airflow temperature ranged from room temperature to 380 °C. The experimental results indicate that environmental factors have a significant influence on droplet ignition probability, ignition probability corresponds with the airflow temperature but is opposite to the airflow rate. Furthermore, the degree of influence on ignition probability varies with the type of combustible liquid. The critical temperatures for non-ignition and sure-ignition on hot surfaces for No. 3 Jet Fuel and Mobile Jet Oil II under ventilation conditions have been acquired. Additionally, an empirical model is established to determine the ignition probability of No. 3 Jet Fuel under ventilation. The results of this work have instructional significance for aircraft fire protection design and airworthiness certificate of aircraft fire safety.