ID 4

Drop size measurements from miniaturized air blast atomizers

 

Abstract:

Lean premixed combustion is the foundation of low emissions industrial gas turbine operation across many applications. For liquid fuels such as Jet-A or #2 diesel, vaporization is a governing factor in achieving low emissions. Vaporization is a function of temperature and pressure in the premixing zone and is crucially dependent on fuel drop size. Many correlations for atomizer performance have been generated for diffusion flame aero engine fuel injectors, where fuel injector diameter is on the order of 30-40 mm. For industrial engines in the 1-30MW class, premixing zone dimensions are small, requiring small atomizers to be employed, typically 10-15 mm diameter, and fuel flow rates and atomizing air flows are commensurately smaller. Three published correlations were tested against measured drop sizes from a small research air blast atomizer whose components could be varied to achieve different degrees of fuel and air mass flow and swirl. Results indicated that the correlations tended to over-predict Sauter Mean Diameter for small atomizers and, therefore, should only be used for initial concept design assessment and predicted performance would require independent verification.