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EXPERIMENTAL AND NUMERICAL STUDIES ON A CONTROL OF LIFTED PHENOMENA IN NON-PRIMIXED HYDROGEN JET FLAMES

Hiroyuki Sato
Department of Mechanical Engineering, Aoyama Gakuin University 5-10-1 Fuchinobe, Sagamihara, Kanagawa 229-8558 Japan

Yasuo Yamazaki
Department of Mechanical Engineering, Aoyama Gakuin University 5-10-1 Fuchinobe, Sagamihara, Kanagawa 229-8558 Japan

A. Koichi Hayashi
Department of Mechanical Engineering, Aoyama Gakuin University, Kanagawa, Japan

Resumo

Stabilization of the non-premixed hydrogen lifted jet flame is investigated experimentally and numerically. Fuel injection velocity is varied to 1300 m/s. In this study, with the visualization technique using a high-speed Schlieren method, effect of shoulder which means the diameter of nozzle rim and influence of fluid dynamic interaction on the lifted phenomena of high-speed jet flames are examined to clarify the control factors of lift-off height and noise level. Over a wide range of fuel jet velocity, three typical flames are observed. Other aspects in this research are noise level, NOx level, and control method for reducing the lift-off flame height. As for the effects of shoulder defined as an external nozzle diameter, the lift-off height of turbulent flames is reduced and noise level is decreased in the cases of high-speed fuel jet conditions. These results are coupled each other. The shoulder is not effective for the reduction of NOx level. As for the influences of fluid dynamic interaction on the lifted phenomena, two types of the control methods are carried out experimentally. One of them is a perpendicularly flow-in type, which is established with the air nozzle injected at right angles from four directions into the main jet. Another is a tangentially flow-in type, where the air is injected tangentially into the main lifted flame. As a result, it is found that the tangentially flow-in type is better than the perpendicularly flow-in type to control the lift-off height due to the effective mixing between fuel and air.