Cavitation Erosion Behavior Of Emulsified Biomass Fuel/Diesel Blends

With the growing shortage and soaring price of petrochemical fuel, thebiomass fuel is regarded as an ideal alternative fuel of diesel, which has a goodapplication prospect because of more resources for raw material and less pollution.The present thesis is to study the cavitation erosion behavior of different materialsin varied fuels by using a magnetostrictive-induced cavitation vibratory apparatusin order to provide some bases for the application of biomass fuel in diesel engine.Firstly, it was investigated that cavitation erosion property of pure copper inthe diesel fuel and emulsified biomass fuel/diesel blend (5wt%biomass fuel inblend) respectively. It was also studied that cavitation erosion performances ofthree kinds of metal (Cu, GCr15and1Cr18Ni9Ti) in the emulsified biomassfuel/diesel blend (10wt%biomass fuel in blend). The results showed that the bubblecollapsing could also take place cavitation erosion in the emulsified biomassfuel/diesel blend although its viscosity was high. The weight loss induced by purecavitation was52.6%of total weight loss by cavitation erosion. The cavitationerosion damage of GCr15was more severe than that of1Cr18Ni9Ti, whichindicated that that corrosion played a great role in the weight loss by cavitationerosion.Secondly, it was detailed with the cavitation erosion behavior of GCr15in theemulsified biomass fuel/diesel blends with different weights of biomass fuel. Thecavitated surface morphology was observed by optical microscope and scanningelectron microscope (SEM), and the effects of three kinds of blends (5wt%,10wt%and20wt%biomass fuel) on the cavitation erosion of GCr15were evaluated bymass loss method. The experimental results showed that the maximum mass lossand the worst cavitation damage were token place in the blend with20wt%biomassfuel. The weight loss was47.2mg and some pits with a diameter of6-12μm andsome obvious cracks around were appeared. It was indicated that the cavitationerosion effect increases with the biomass fuel content in the emulsified biomassfuel/diesel blend.Finally, the effect of surface roughness of metal material on the cavitationerosion in the emulsified biomass fuel/diesel blend (10wt%biomass fuel) was studied via mass loss analysis and SEM. The results showed that surface roughnesshad a great impact on the cavitation erosion of metal in the corrosive blend. Thecumulative mass loss of G3sample (Ra=0.28μm) was1.4times than that of G1sample (Ra=0.05μ m) in the blend. The synergistic effect of cavitation andcorrosion was more obvious when Rawas0.28μm. Thus, the material surfacedamage became serious，However, the mass loss rate would be lower because thesurface became smooth with cavitation.