Influence of a cooled wall on droplet stream combustion

Experiments were performed to investigate combustion characteristics of droplet streams in the vicinity of a cooled wall. The droplets were composed of methanol/dodecanol mixtures or methanol. A flat-flame burner generated hot gases that were directed down an electrically heated flow tube. Droplets initially about 160 or 193 mum in diameter were injected through the center of the flat-flame burner and along the tube. The droplet stream, which ignited shortly after entering the tube, passed near a vertical flat water-cooled wall with a sharp leading edge such that the droplets were within the thermal and momentum wall boundary layers. The experiments indicate that burning rates decreased significantly when droplets were in the vicinity of the wall. The wall also influenced staged combustion behaviors of the droplet streams. In addition, flame characteristics (sooting and flame lengths) were influenced by the presence of the wall.