An Experimental Study on Flame Behavior with Porosity of Center Plate in a Low-swirl Combustor

摘要

This study investigated the effect of porosity of the center plate on the combustion characteristics in a low-swirl combustor. The swirl number was 0.42 while the swirler angle was fixed to 37degree. For the turndown ratio, it was confirmed that the flame as a laboratory scale is stable up to 21 kW and it's also stable even over higher thermal power. As a result, it was found that the flame height increased and the flame shape was changed from V shape to flat shape with increasing porosity of center plate. Although the flash back caused by increased porosity was suppressed, the lean flammability limit in stability map was decreased. Because the low swirl combustion has no internal recirculation zone, the middle flow pattern of the swirler had relatively uniform flow with a constant velocity across the center plate. So, as the porosity of center plate increases the heat loss of the combustor wall decrease with a reduction of the external recirculation zone which made the inner temperature conditions of combustor to increase. Consequently, the emission of NO_x and CO increased with porosity increasing.