The Relationship Between Flame Stability and Drag of Bluff-Body Flameholders

The main purpose of this investigation is to establish a relationship between the blowoff velocity of a bluffbody flameholder and its drag coefficient. To this end, numerous measurements of blowoff velocity and drag coefficient are carried out on various forms of two-dimension al flameholders. They include conventional Vgutters of the type widely employed in turbojet afterburners, and "single-sided" flameholders that are characterized by a single-vortex flow pattern in their wake region. The test program covers wide ranges of effective pressure ratio obtained using the water injection technique, and it also includes variations in velocity, flameholder size, and flameholder blockage. The results confirm previous findings in regard to the strong influence of drag coefficient on blowoff velocity. They also provide a satisfactory explanation for the previously reported superior flameholding properties of single-vortex systems over double-vortex systems.