CARS Measurements of Temperature Profiles Near a Wall in an Internal Combustion Engine

Broadband, coherent anti-Stokes Raman scattering (CARS) measurements of burned gas temperatures near a wall in an internal combustion engine have been performed. A lens-prism arrangement was used to traverse the probe volume perpendicular to the cylinder head wall while maintaining the alignment of the CARS optical system. The spatial resolution of the measurements was approximately 25-50 μm, and CARS signals were obtained at distances within 25 μm of the wall. Temperature profiles were measured 0.6, 2.7 and 4.2 msec after peak pressure was reached. A power law expression for the temperature profile in the boundary layer was optimized to achieve good agreement between measured and predicted profiles. The thickening of the boundary layer during the piston expansion stroke was clearly evident.