OCR Text |
Show 1.3.5 upstream of the test section ensured the uniformity of axial velocity profile within + 5% over the middle two-thirds of the cross section of the chamber to which the flames were confined. Fuel was supplied to the nozzle from a storage tank pressurized with nitrogen and measured with calibrated rotameters. The atomization air was supplied to the nozzle through flow regulators and metered with rotameters. Since the cross section of the chamber was considerably larger than that of the flame (by a factor of about 50), the flames of this study could be considered essentially unconfined. The isolation of the effects attributable to differences in atomization characteristics from the overall effects of emulsification of fuel on flame characteristics was not intended in this study. However, in order to minimize the effects due to differences in atomization of neat fuels, the mean droplet size was measured in the near-nozzle region (at x = 10 mm where x is the axial distance from the nozzle) by impaction method and the atomization gas flow rates were ajusted to keep it at 70+10 ym for both fuels. Table 1 shows the nominal values of experimental conditions. The gas analysis instrumentation comprised of a fluorescent SOo analyzer (Thermo Electron, Model 40), a chemiluminescent NO analyzer (Thermo Electron, Model 10A), a nondispersive infrared CO analyzer (Horiba, Model Mexa 221) and a polarographic 0~ analyzer (Ventronics, Model 5573). The gas sampling system consisted of a quartz probe mounted on a traversing mechanism capable of positioning the probe with a precision of 0.5 mm. The probe had an internal diameter of 5 mm and was reduced to an orifice of diameter 1 mm with an internal taper of 4°. The probe was uncooled and teflon lines were used for all connections. A |