An optical comparison of the cavitation characteristics of diesel and bio-diesel blends in a true-scale nozzle geometry

This study undertakes an optical comparison of the cavitation phenomena present in a true-scale optical diesel injector at fuel injection pressures up to 2000 bar. The cavitating nozzle-flow characteristics of rapeseed methyl ester B20 and B100 bio-diesel blends are compared to those of standard ultra-low sulphur petroleum diesel as a means to establish any potential differences in fuel injector performance when bio-fuel blends are introduced to the fuel injection system. A difference in the propensity for cavitation to form is shown, with cavitation inception observed earlier in the 2 ms fuel injection event tested for the bio-diesel blends, with B20 cavitating more readily than B100. Once cavitation inception has occurred, the characteristics of the flow appear to be no different to those of petroleum diesel for fuel injection pressures up to 2000 bar.