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

The three-dimensional gas velocity and fuel concentration field in the turbulent mixing zone of a natural gas swirl burner have been investigated in the isothermal case by means of laser Doppler anemometry (LDA) and laser sheet visualisation (LSV). The two techniques enabled useful insight into the fully turbulent, three-dimensional swirling flow to be gained for various operating conditions and fuel injection typologies. The effect of swirl number and fuel injection mode, radial or coaxial, has been quantified on both the flowfield structure and fuel concentration distribution. The results indicate that the unmixedness index, U, may be a significant parameter to judge the mixing efficiency due to swirl strength and fuel-air momentum ratio in a specific burner geometry, at least under isothermal conditions in the near-held zone downstream the quarl exit. (C) 2000 Elsevier Science Inc. All rights reserved.