TY - JOUR
T1 - Effects of fuel properties on the burning characteristics of collision-merged alkane/water droplets
AU - Wang, C. H.
AU - Pan, K. L.
AU - Huang, W. C.
AU - Wen, H. C.
AU - Yang, J. Y.
AU - Law, Chung King
N1 - Funding Information:
The work at National Taiwan University was supported by the National Science Council of Taiwan, ROC, and that at Princeton University was supported by the US Air Force Office of Scientific Research.
PY - 2008/4
Y1 - 2008/4
N2 - The combustion characteristics of freely falling droplets, individually generated by the merging of colliding alkane and water droplets, were experimentally investigated. The outcome of the collision droplets was firstly studied and then the subsequent burning processes such as the flame appearance, ignition and burning behaviors were recorded, through either visual observation or microphotography with the aid of stroboscopic lightening. If the merged droplets were exhibited in an insertive manner, while the water droplet inserted into the alkane droplet, these yield the burning behaviors prior to the end of flame were very much similar to that of pure alkane. The burning was ended with droplet extinction for lower-C alkane, and with either droplet "flash vaporization" or extinction for hexadecane. And if the merged droplets were in adhesive manner, for hexadecane with large water content, they either could not be ignited for the large merged droplets, or be ignited with a much prolonged ignition delay, followed by a soot-reducing flame and an ending of droplet extinction for the small merged droplets. "Homogeneous" explosion was not observed in any of the tests, and "heterogeneous" explosion, induced by trapped air bubbles, occasionally occurred for merged droplets with C-atom in alkane is higher than dodecane. And the sudden disappearance of droplet definitely decreased the burning time and thus enhanced the burning intensity. Besides, the fuel mass consumption rates were increased, even in the cases that having droplet extinction, because of the enlargement of the surface area due to the stuffing of water droplet.
AB - The combustion characteristics of freely falling droplets, individually generated by the merging of colliding alkane and water droplets, were experimentally investigated. The outcome of the collision droplets was firstly studied and then the subsequent burning processes such as the flame appearance, ignition and burning behaviors were recorded, through either visual observation or microphotography with the aid of stroboscopic lightening. If the merged droplets were exhibited in an insertive manner, while the water droplet inserted into the alkane droplet, these yield the burning behaviors prior to the end of flame were very much similar to that of pure alkane. The burning was ended with droplet extinction for lower-C alkane, and with either droplet "flash vaporization" or extinction for hexadecane. And if the merged droplets were in adhesive manner, for hexadecane with large water content, they either could not be ignited for the large merged droplets, or be ignited with a much prolonged ignition delay, followed by a soot-reducing flame and an ending of droplet extinction for the small merged droplets. "Homogeneous" explosion was not observed in any of the tests, and "heterogeneous" explosion, induced by trapped air bubbles, occasionally occurred for merged droplets with C-atom in alkane is higher than dodecane. And the sudden disappearance of droplet definitely decreased the burning time and thus enhanced the burning intensity. Besides, the fuel mass consumption rates were increased, even in the cases that having droplet extinction, because of the enlargement of the surface area due to the stuffing of water droplet.
KW - Collision-merged droplet
KW - Extinction
KW - Flash vaporization
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U2 - 10.1016/j.expthermflusci.2007.11.020
DO - 10.1016/j.expthermflusci.2007.11.020
M3 - Article
AN - SCOPUS:40949156216
SN - 0894-1777
VL - 32
SP - 1049
EP - 1058
JO - Experimental Thermal and Fluid Science
JF - Experimental Thermal and Fluid Science
IS - 5
ER -