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Show 9 Flame and Flow Visualization of Perforated Porous Plate To examine the state of flames in more detail, the flame shapes were observed by taking both direct photographs and high-speed video photographs. The flow on the porous plate in the non-combustion state was also visualized by using laser tomography and highspeed video photographs. These observations of the flame show that percolation flames are formed between the port flames as shown in Fig. 11. Observations of the flow of the unburned mixture over the perforated porous plate by laser tomogrphy shows that a recirculation flow is formed between the port flows. The state of the flow is shown in Fig. 12. In combustion experiments using the porous plate burner without perforations, the percolation flow velocity reaches 1 m/s or higher as the burner internal pressure is increased. As a result, flat percolation flames cannot be stabilized on the surface and lifted flames are observed. On the other hand, with the perforated porous plate, percolation flames are formed even when the percolation flow velocity through the porous part is more than 4 ml s. This may be because the percolation flow is suppressed by the recirculation flow caused by the high port flow, and percolation flames are formed at the position where its flow velocity is equal to the burning velocity. These percolation flames then stabilize the port flames. In this way, in perforated porous plate burners, the percolation flow and the port flow have a good effect on each other, and a high combustion perfor-mance can be obtained. 1.t ~ /\Po"trt ~F'lotw Recirculation Flow ' '\J!I ql s ~ ~ j 1 \ ,s ~ ,~ : ~ "\. Ai'" fl Fig-l2 Flow of perforated porous bl |