Mixture Strength Measurements in the Combustion Chamber of SI Engine via Rayleigh Scattering

Abstract

The laser Rayleigh scattering technique was applied for the space resolved measurements of vapor concentration in the concentration in the combustion chamber of a multipoint injection spark ignition engine for automotive use. The mixture formation during the intake stroke was simulated by the timed or continuous injection of freon 113 (liquid) or freon 12 (gas) into the steady flow of dust-free dry air through an intake port. The vapor concentration in the transparent combustion cylinder was determined from the intensity of scattered light which had been calibrated beforehand. The results showed that the present optical system was found to be successful in determining the local vapor concentrations for both liquid and gaseous fuel injections. It was also evident that the highly heterogeneous field of vapor concentration was established in the combustion cylinder. The vapor concentration profile was largely affected by the place for fuel injection and the intake valve lift.