N ₂ CARS Thermometry in Diesel Engine

CARS* THERMOMETRY in diesel engine is reported. Spatially and time resolved spectra of N₂ CARS spectrum considered both temperature and pressure dependence has been developed. Temperature distribution on 20mm below the cylinder head are measured at any crank angle. N₂ CARS spectra obtained do not conform to any spectra of homogeneous N₂ at 1 atmosphere because of high pressure and high temperature in the cylinder. So the simulation program which takes account of pressure narrowing has been developed. Though the results of calculations and experiments are coincident with each other, it would be complicated to derive the temperature from the contour of the N₂ spectrum. A careful consideration, however, shows that the line width at 1/5 height is sensitive to temperature but rather insensitive to ambient pressure. In this experiment the temperatures are determined from 1/5 band width and temperature distributions in diesel engine cylinder based on CARS are obtained.