Stratification features in DI gasoline combustion were studied using a constant-volume combustion vessel. Indicated pressure analysis and high-speed combustion observation were carried out by changing injection-sparking interval τ
int, spray cone angle and swirl ratio. There exists a τ
int range where the mixture is ignitable and the shortest τ
int gives the highest maximum pressure rise rate (
dP/
dt)
max and the highest (
dP/
dt)
max reaches a maximum at a certain swirl ratio. The fairly large scatter found in(
dP/
dt)
max data plotted against τ
int is markedly reduced by plotting them against total ignition delay τ
tot(=τ
int+τ
d), where τ
d denotes ignition delay. Maximum volumetric burning velocity (
Sv)
max was proposed as a measure of the stratification degree, based on the thermodynamic analysis which was carried out under the concept that a higher stratification degree increases the stoichiometric range of the mixture. It is noteworthy that as the spray cone angle is increased, (
Sv)
max increases and becomes less affected by
SR.
抄録全体を表示