Study On Spray Quality Evaluation Of DME/Diesel Mixed Fuel

This paper using high resolving power digital camera on dimethyl ether/diesel mixedfuel to study spray characteristics. Using Malvern method and PIV on pure diesel to studyspray characteristics. And using the fortran language to calculate the three design point offlash photography method with different DME mixed watio and the design point wasmeasured by Malvern and PIV. By calculation, the fuel droplet size number distribution canacquired.The main research method of the flash photography method is change the aperture andinjection pressure of fuel injector, and change the DME mixed ratio. Though this method,thebest aperture and injection pressure of fuel injector and DME mixed ratio can acquired. Inaddition, using the results of Malvern method and PIV to compared with the result of flashphotography method.In experiment, the injection pressure are16Mpa and17Mpa and20Mpa, the DMEmixed ratio are0%,10%and20%(with the different of DME mixed ratio, the mixed fuel isnamed D0, D10, D20.), the injector aperture are0.26mm,0.315mm and0.383mm. The maincontent of the test is divided into four parts: First, when the injection pressure for20Mpa,DME mixed ratio for20%, aperture for0.26mm,0.315mm and0.383mm, the spraycharacteristics of mixed fuel was measured; Second, when DME mixed ratio for20%,aperture for0.315mm and injection pressure for16Mpa and17Mpa and20Mpa, thespray characteristics of mixed fuel was measured; Third, when aperture for0.315mm,injection pressure is20Mpa, DME mixed ratio was0%,10%and20%, the spraycharacteristics of mixed fuel was measured; Fourth, using the Malvern spraytec measure thespray characteristics of mixed fuel with injection pressure for20Mpa, DME mixed ratio for0%(pure diesel) and aperture for0.315mm.Droplet size distribution function and joint droplet size and velocity distribution functionare derived by Cao Jianming based on the maximum entropy principle, the law ofconservation of mass and the law of conservation of momentum. On this basis, usingFORTRAN powerstation4.0software, program code, calculate the three design point of flash photography method with different DME mixed watio and the design point was measured byMalvern and PIV. By calculation, the fuel droplet size number distribution can acquired. Bycalculation, the initial values of Lagrange factor coefficients are acquired.The results show that: First, with the aperture decreases, spray quality better, wave moveto left, all of the length mean diameter, the volume mean diameter and the Sauter meandiameter are decrease; Second, with the injection pressure increases, spray quality better,wave move to left, all of the length mean diameter, the volume mean diameter and the Sautermean diameter are decrease; Third, with the DME mixed ratio increases, spray quality better,wave move to left, all of the length mean diameter, the volume mean diameter and the Sautermean diameter are decrease.