Application of the LIF/Mie Technique to an Aeronautic Kerosene Jet A-1 Spray Injected under Relight Conditions

Certification process of an aircraft engine requires the engine to be able to relight under high-altitude conditions. This capability is strongly affected by the characteristics of the spray injected into the combustion chamber, by means of an aeronautical injection system. The understanding of the atomization process is a key factor in order to forecast the engine's relight capability. Among the parameters of interest (gas-phase velocity, concentration and liquid volume fraction), the droplet size is essential. In the literature, this parameter is commonly characterized under ambient temperature and pressure conditions. The present study focuses on the application of the LIF/Mie technique for the characterization of an aeronautic kerosene Jet A-1 spray injected under relight conditions. A qualitative study of the effect of liquid temperature and injection pressure on the Sauter Mean Diameter is first presented. The technique is then applied under critical high-altitude conditions and provide quantitative SMD mappings. Comparisons with PDA measurements exhibit a very good agreement, which validates the LIF/Mie technique as a reliable tool for studying sprays in these harsh conditions.