UC Irvine

Isooctane, and mixtures of isooctane with various ring and aromatic compounds blended to yield the same smoke point were separately injected through a twin-fluid atomizer into a turbulent, swirl-stabilized model combustor. A nonintrusive optical probe based on larege angle (60°, 20°) intensity ratio scattering was used to yield a point measurement of soot particulate in the size range of 0.08 to 0.38 μm. The velocity and temperature fields were characterized by a two-color laser anemometer and thermocouple, respectively. Sooting was low or nonexistent in regions of high temperature and relatively high in regions of depressed temperature. The addition of ring compounds to isooctane increased the amount of soot produced and changed the location of peak soot production. The total amount of soot produced depended on fuel type for those fuels of equivalent smoke point, with the double ring compounds yielding significantly more soot than the single ring blend. The amount of soot produced was reduced by a reduction in fuel loading. Scanning electron micrographs of extracted samples established that the optical technique resolved the large particle wing of the soot size distribution. The results point to the complexity of soot production in flows dominated by strong aerodynamics, and the importance of nonintrusive optical measurements to both unravel the processes of formation and burnout and provide the information necessary to guide combustor and nozzle design. © 1985 Combustion Institute.