RESUMEN
New diagnostics are presented that use a digital camera to measure full-field soot temperatures and soot volume fractions in axisymmetric flames. The camera is a Nikon D700 with 12 megapixels and 14 bit depth in each color plane, which was modified by removing the infrared and anti-aliasing filters. The diagnostics were calibrated with a blackbody furnace. The flame considered here was an 88 mm long ethylene/air co-flowing laminar jet diffusion flame on a round 11.1 mm burner. The resolution in the flame plane is estimated at between 0.1 and 0.7 mm. Soot temperatures were measured from soot radiative emissions, using ratio pyrometry at 450, 650, and 900 nm following deconvolution. These had a range of 1600-1850 K, a temporal resolution of 125 ms, and an estimated uncertainty of ±50 K. Soot volume fractions were measured two ways: from soot radiative emissions and from soot laser extinction at 632.8 nm, both following deconvolution. Soot volume fractions determined from emissions had a range of 0.1-10 ppm, temporal resolutions of 125 ms, and an estimated uncertainty of ±30%. Soot volume fractions determined from laser extinction had a range of 0.2-10 ppm, similar temporal resolutions, and an estimated uncertainty of ±10%. The present measurements agree with past measurements in this flame using traversing optics and probes; however, they avoid the long test times and other complications of such traditional methods.
RESUMEN
A novel thin-filament pyrometer is presented. It involves a consumer-grade color digital still camera with 6 megapixels and 12 bits per color plane. SiC fibers were used and scanning-electron microscopy found them to be uniform with diameters of 13.9 micro m. Measurements were performed in a methane-air coflowing laminar jet diffusion flame with a luminosity length of 72 mm. Calibration of the pyrometer was accomplished with B-type thermocouples. The pyrometry measurements yielded gas temperatures in the range of 1400-2200 K with an estimated uncertainty of +/-60 K, a relative temperature resolution of +/-0.215 K, a spatial resolution of 42 mum, and a temporal resolution of 0.66 ms. Fiber aging for 10 min had no effect on the results. Soot deposition was less problematic for the pyrometer than for the thermocouple.