抄録
Laser Rayleigh scattering was applied for remote, nonintrusive point probing of the vapor concentration and its fluctuation near the spark plug of a motored spark ignition engine, which was caused by the intermittent injection of Freon-12 vapor into an intake port. The theoretical analysis showed that the instantaneous fuel vapor concentration can be split into three components : the ensemble-averaged mean concentration, the cyclic variation of temporal mean concentration and the temporal concentration fluctuation in a specific cycle. This paper concentrates on the measurements of the ensemble-averaged mean concentration and the cyclic variation of temporal mean concentration. The results show that both the ensemble-averaged mean concentration and the cyclic variation of temporal mean concentration increase and reach a peak, after which they decrease during the intake and compression strokes. Moreover, they are strongly affected by air-fuel ratio, engine speed, injection duration and injection timing.
