Effect of Gasoline Fuel Additives on Combustion and Engine Performance

5.1.3
 
Effect 
o
f Additives on Base Gasoline Fuel 
Fuel additive effects were initially tested through droplet sizing methods. All 
additive measurements were preceded by base fuel tests, after which the base fuel with 

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5.1 Gasoline Spray Investigations with Additives 
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the additive at the recommended treat rate and then ten times the treat rate was tested. 
Base fuel data obtained between all additive experiments was used for estimating 
experimental repeatability and additive measurements were compared against its 
standard deviation (displayed as dashed lines in this section).
The largest experienced change to SMD from additives was seen for drag 
reducing agent DRA. SMD results for minimum transmissions have been displayed in 
Figure 5.1. It can be seen that although the changes are very small in relation to the 
base fuel, DRA at 10X seems to suggest an increase in droplet size. Similar change in 
SMD could be seen for the 50 % transmission case.
Figure 5.1: SMD for gasoline with DRA additive at minimum transmission 
Same behaviour could not be fully seen for DRB additive as displayed in 
Figure 5.2. As discussed in Section 2.1.4, drag reducing agents can break down under 
turbulent conditions. It is shown in Appendix B that Reynolds numbers of up to 23,000 
were experienced in present investigations, suggesting very high levels of turbulence 
that is thought to cause the breakdown of agglomerates of the drag reducing agents. 
This might suggest that the DRA agglomerates are larger or more shear resistant than 
those of DRB.
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