Abstract
A lifted flame allows partially premixed combustion of hydrogen without flashback for dry low-NOx gas turbine combustors. The use of a small injection hole enhances the shear mixing of hydrogen with air. The objective of this study is to investigate the effect of the hydrogen injection hole diameter on the burning condition of lifted flames. Five hydrogen injectors with hole diameters varying from 0.2 mm to 1.0 mm were used. The hydrogen injection pressure drop, flame stability, flame appearance, NOx emissions, and combustion efficiency were evaluated. As the injection hole diameter decreased, mixing became more uniform, resulting in a decrease in NOx emissions, although the difference in value was small for hole diameters ranging from 0.8 mm to 0.4 mm. On the other hand, both the injection pressure drop and flame stability became issues for the 0.4 mm and 0.2 mm injectors.
