Effect of injection topology on turbulent homogeneous mixing in a natural gas swirl burner

Results of an experimental characterization of the isothermal mixing process in near field of natural gas burners are reported. The main parameters investigated were air swirl, fuel inlet geometry, and fuel to air velocity momentum. The optical techniques used were all based on the Mie scattering principle: laser Doppler anemometry and laser sheet visualization integrated by quantitative image analysis. The preliminary results indicate that the unmixedness index, U, may be a significant parameter to judge the mixing efficiency of a specific burner geometry, being sensitive to the swirl strength and the fuel-air momentum ratio. (AIAA)