Experimental Evaluation of a Premixed Swirl-Stabilized Gas Burner With a Focus on Mixture Stratification

This is the authors' abstract. We don't add key points for this paper.

The present work reports an experimental evaluation of the flame stabilization, structure and pollutant emissions for a swirl-stabilized premixed burner at atmospheric conditions. The burner has been designed to accommodate two inlet streams, namely a swirling air and a non-swirling fuel-air mixture, which are fed into a mixing chamber. By modifying the air mass distribution between the swirling and non-swirling streams, the burner can produce different swirl numbers at the chamber, as well as different fuel-air mixture stratification. A central tube acts as a bluff body to help stabilize the flame. Experimental diagnostics include high speed flame visualization in terms of OH* chemiluminescence, and NOx pollutant at the burner outlet. The study has been carried out using both hydrogen and methane as fuels. A sweep of conditions has been carried out to identify the lean blow-off limit over the burner operational map. Results for methane indicate that the lean blow-off limit is strongly affected by the air distribution between the swirling and non-swirling parts. In contrast, air distribution has a more significant effect on NOx emissions for hydrogen. Different flame shapes are analyzed over the operational map, where strong differences in lift-off, flame width, and reaction zone chemiluminescence have been identified.