Mixture Strength Measurements in the Combustion Chamber of SI Engine via Rayleigh Scattering. (5th Report, Concentration Profiles near the spark Plug and Intake Valves in s Steady Flow Test).

Abstract

Extensive measurements were made of the fuel vapor concentration profiles near the spark plug and intake valves of a spark ignition engine during the intake stroke via the application of laser Rayleigh scattering, which can give an accurate measurement of the fuel vapor concentration with highly spatial and temporal resolutions. The mixture formation in the combustion chamber was simulated by the continuous injection of Freon-12 into the steady dust-free dry air flow through an intake port. The experimental results showed that the present experimental apparatus was effective for performing detailed measurements of the fuel vapor concentration and its fluctuation accurately near the spark plug and intake valves. It was also noted that the stereoscopic spatial distributions of the mixture strength can be derived from the experimental results. The concentration profiles near the spark plug and intake valves were largely affected by the intake valve lift and its configuration.