A Study on the Application of the Two–Color Method to the Measurement of Flame Temperature and Soot Concentration in Diesel Engines

Flame temperature and KL factor in a DI diesel engine are measured optically by the two-color method. Some differences are observed between the measure values at visible and infrared wavelengths. These differences are caused by: (1) effect of change of index α in time at infrared wavelength during combustion period; (2) effect of distributions of temperature and soot concentration along optical path; and (3) effect of reflection at the walls.

The optical characteristics and some other problems on the instrumentation of the two-color method at both wavelengths are also discussed.