LAUSR

Abstract The gas temperature fields of axisymmetric co-annular laminar diffusion ethylene flame jets in air and oxygen-enriched atmospheres were measured and visualized using large lateral shearing interferometry. The relationship between the refractive index and the temperature is obtained using a state equation and the Gladstone–Dale relation. Considering the unknown local gas composition can be a potential source of error, local gas compositions provided by corresponding numerical simulations were employed. The spatial resolution of the temperature fields was 0.1 mm/pixel. The temperature results obtained using hot air assumption and simulated local composition indicate that deviations of up to 400 K occur at the bottom part on the centerline, whereas at larger axial or radial positions, the deviations could be less than 50 K. The results are also validated by comparison with CARS. In addition, compared with flames under air atmosphere, significant deviations occurred in a greater region of oxygen-enriched flames.