Photo Contest

2005 Photo Contest -Beautiful Flames- The HIGHEST AWARD


Rotating Flamelet
Hiroyuki TORIKAI
Energy Technology Research Institute, AIST

The ring-shaped flame is a methane air diffusion flame formed in the stagnation region of an axisymmetric impinging jet. The inner edge flame is formed as a flame base and determines stability of the whole flame The airflow issues from a converging nozzle and impinges on a round plate. A ring-shape sintered porous metal is embedded in the impinging plate. The inner diameter of the porous metal is 10 mm. The methane flow is supplied from the porous area. The fuel injection velocity and the stagnation velocity gradient are 2.1cm/s and 46 1/s, respectively. Part of the edge flame is blown off with decrease in the fuel velocity. As the fuel velocity decreases more, the blowoff are increases in a circumferential direction. Finally, the whole flame is blown off. In the blowoff process, it is observed that the remaining flamelet rotates at constant speed above the porous area like merry-go-round. The three pictures show the flamelet that rotates in an anti -clockwise direction at 11 Hz with rotation frequency. The fuel velocity and the stagnation velocity gradient are 1.4 cm/s and 46 1/s, respectively. The exposure time of the pictures is 1/200 s. The rotating flamelet is considered as a partially premixed flame and propagates in a circumferential direction through a premixing layer which is formed by inter-diffusion between air and methane in the blowoff region.