Abstract
A technique for flame diagnostics was developed, in which the luminescence images of OH, CH and C2 radicals were visualized and processed. Both short-exposure images and time-averaged ones of these radicals were obtained for nonluminous flames. For luminous flames, on the other hand, luminescence images of OH and CH radicals were separated very accurately from the intense background emissions. This was done by processing the monochromatic images of a flame in and around the radical luminescence band obtained using a set of interference optical filters and an image intensifier. The details of the technique were established by spectroscopic observation of a Wolfhard-Parker flame or a turbulent Bunsen flame as well as the computer simulation based on the images. The accuracy of the obtained luminescence images of radicals was evaluated by comparing them with monochrometer data. The present technique is appropriate for the direct visualization of the flame reaction zone and is applicable to industrial flames to which the PLIF technique is difficult to apply.
