Study On Spray Quality Evaluation Of Biodiesel/Diesel Mixed Fuel

Spray technology has been widely applied to the production and livelihood of the vast majority of mankind areas. In combustion equipment, spray will affect the quality of ignition, combustion efficiency, combustion stability, temperature distribution, exhaust pollution and other aspects of performance. There is closely relationship between spray combustion technology and the progress of combustion technology. They promote each other in the progress [1]. Spray quality evaluation is too vitally important because of the importance of the spray. More influencing factors can be research in details by theoretical calculations, which can not be replaced by experimental study.Droplet size distribution function and joint droplet size and velocity distribution function are derived by Cao Jianming based on the maximum entropy principle, the law of conservation of mass and the law of conservation of momentum. The comparison research between diesel and diesel/bio-diesel, B0(Biodesel liquid quality accounted for 0 percent of the diesel/bio-diesel mixed liquid), B24(Biodesel liquid quality accounted for 24 percent of the diesel/bio-diesel mixed liquid), MB24(Biodesel ,ethonal and addtive liquid quality accounted for 24,1 and 0.01 percent of the diesel/bio-diesel mixed liquid), B50(Biodesel liquid quality accounted for 50 percent of the diesel/bio-diesel mixed liquid), B100(Biodesel liquid quality accounted for 100 percent of the diesel/bio-diesel mixed liquid), sprays was analyzed by using high resolving power digital camera.On this basis, this paper established the diesel and biodiese spray droplet size distribution model. And the comparative analysis showed that the calculation results fits well with the experimental data. And joint droplet size model for diesel and biodiesel is established. The computation program is programmed by FORTRAN language. The prediction on joint droplet size distribution for diesel and biodiesel is conducted. The results show that with bio-diesel mixed ratio increases, fuel viscosity enlarge, spray core angle decrease, Sauter mean diameter increase. Sauter men diameter of pure diesel is slightly larger than that of MB24 because of pure diesel's larger relative size range and dispersion boundary. Sauter men diameter of MB24 is smallest because of ethanol's dilutedness, and spray quality is improved evidently. It can be seen that all of curve peaks of fuel droplet size number distribution in various mixed fuel is located at 14mμ, smaller size droplets are more. It can also be observed that with bio-diesel mixed ratio increase, the curve peaks of droplet size number distribution go down, and the curves tend to even. It is indicated that fuel droplet size number distribution in spray tend to uniform gradually with fuel viscosity increases. The results also show from droplet cumulate volume distribution that with bio-diesel mixed ratio increases, the droplet diameter which reach a curtain cumulate volume increase, and larger drops become more..The paper also primarily probe into the effect on the model from the initial guess of the Lagrange factor. After repeated attempts, it finds that Lagrange factor could be a good convergence when the initial values of Lagrange factor coefficients are 1.17—1.21 for the joint distribution of diesel and biodiesel.