Measurements of Soot Temperature in a Diffusion Flame Using a Digital Camera

Abstract

Temperatures were measured in a laminar axisymmetric diffusion flame with a digital camera. The camera was a Nikon D700, modified to remove the Infra-Red (IR) cut filter and the anti-aliasing filter. Temperatures were obtained using ratio pyrometry at 550, 650, and 900 nm following deconvolution. The camera was calibrated with a blackbody furnace. Measurements were made for an 88 mm high laminar ethylene/air diffusion flame in co-flow on a burner with an 11.1 mm inside diameter. Soot temperatures were measured in the range of 1250 - 2000 K with an estimated uncertainty of ±60 K. The diagnostic requires axisymmetric, optically thin flames, and regions with temperatures greater than 1250 K and soot volume fractions greater than 0.1 ppm. The results agreed with published measurements for this flame. The new diagnostics provide a convenient and economical way to perform these measurements with good accuracy and spatial resolution.