The Application of Laser Rayleigh Scattering to the Local Mixture Strength Measurements in SI Engine during Intake Stroke

An experimental study was made of the fundamental aspect of the mixture formation in the combustion chamber of automotive spark ignition engine with the multipoint fuel injection. The mixture formation during intake stroke of an engine was simulated by the timed or continuous injection of Freon-113 or Freon-12 into the steady flow of dust-free dry air through an intake port. The vapor concentration in the transparent combustion cylinder was determined with the application of the laser Rayleigh scattering. The results showed that the present optical system was useful for the time and space resolved measurements of vapor concentration in the combustion chamber in the case of liquid and gaseous fuel injections. The spatial distributions of the time averaged vapor concentration were highly heterogeneous. It was also found that the vapor concentration profile was largely affected by the place for fuel injection and the intake valve lift.