Effect of Gasoline Fuel Additives on Combustion and Engine Performance

Figure 3.3: Fuel system components cleaned in the ultrasonic bath. Components include: a) 
high pressure fuel tank lid, b) common rail fuel pressure transducer, c) pressure transducer 
mount, d) high pressure fuel line, e) high pressure fuel tank main body, f) fuel side small 
piston, g) injector cap, h) DI injector 
3.1.2
 
Injection System Characteristics 
Injector characteristics were quantified in order to be able to distinguish 
between hardware variability and additive effects. Additionally, this data could be 
used to determine experimental conditions. Figure 3.4 represents the shot-to-shot
Figure 3.4: Injection signal to injector driver output signal delay 
6.5
6.7
6.9
7.1
7.3
7.5
7.7
7.9
0
5
10
15
20
Dela
y
, 
us
Injection Event, no
a 
c 
d 
e 
g 
h 
b 
f 

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3.1 Spray Investigation 
78 
variability of start of injection signal to start of injector signal. An average delay was 
found to be 7.2 
µ
s with a standard deviation of 0.79 %. This, in comparison to the 
injection signal duration (in ms range), was considered not significant. 
Figure 3.5 displays the increase in fuel velocity with increasing injection 
pressures. The data was obtained from shadowgraph images at each injection pressure 
and was measured to reflect time taken to reach 60 mm from the injector nozzle. Each 
point was measured from a 20 image average that was found large enough sample to 
eliminate the effect of spray-to-spray variability. The measured spray tip velocity 
varied nearly linearly between 38.5 km/h and 51.9 km/h. Shadowgraph images of 
typical injections for 50 bar and 110 bar injection pressures can be seen in Appendix 
A.