Study On Spray Characteristics Of N-Butanol-Diesel Blended Fuel Based On Constant Volume Combustion BOMB

The second-generation biofuel normal-butanol is applied in engines, usually mixed with gasoline as biological alternative fuel or with diesel as mixing biological fuel. Compared with the methanol and ethanol, n-butanol has the advantages of insolubility in water, solubility in gasoline or diesel oil at any proportion, high calorific value and cetane number and low volatility. These advantages make it has a great potential in realizing efficient and clean combustion of diesel engine. In addition, n-butanol is of great significance to reduce the emissions of diesel engines and ease the global energy crisis due to it increases the renewability of oxygen fuel and raw materials. Meanwhile, the spray characteristics have a very direct influence on combustion and emission performance of diesel engine, thus, it is very significant to study the spray characteristics of the n-butanol-diesel blended fuel.First, according to the requirements of the test, a set of experiment equipment had been designed and made which including constant volume combustion bomb, IAT common rail system III, light path system, electronic control system, high pressure nitrogen gas system and high-speed photography system. In order to analyse the spray photo of the test, an image process program had been compiled to import and analyse the image. Then the spray cone angle, through distance and such characteristic parameters could be obtained by image segmentation, extraction of contour edge.Then, this paper aiming at the four kinds of fuels of n-butanol-diesel, n-butanol-diesel-gasoline, diesel-gasoline and diesel studies the spray processes in the condition of in a high pressure (2MPa) constant volume combustion bomb at normal temperature and different injection pressure (100MPa,130MPa and 160MPa). From image processing and analysis we can draw the following conclusion:The integral variation tendency of the spray cone angle and through distance is that with the passage of time, they grow rapidly in initial stage and then growth trend weakens, and finally sizes tend to be stable. The impact of the injection pressure on the spray cone angle is about 4°-5°. For the same fuel, the larger injection pressure, the larger the spray cone angle and through distance. At the same injection pressure, the spray cone angle of four blended fuels from large to small is in the order: the diesel-gasoline > the n-butanol-diesel-gasoline > the n-butanol-diesel > the diesel. While the through distance is in the order: the diesel > the n-butanol-diesel > the n-butanol-diesel-gasoline > the diesel-gasoline. The impact of the injection pressure on the through distance in the n-butanol-diesel and the n-butanol-diesel-gasoline is samller than that in the diesel and the diesel-gasoline.