A study on spray characteristic of gasoline-biodiesel blended under gci engines condition performed on constant volume combustion chamber system

Abstract

This paper presents the study of the spray characteristics of the gasoline-biodiesel fuel mixture at various operating conditions of the GCI (gasoline compression ignition) engine performed in a constant volume combustion chamber (CVCC). Spray development, spray penetration length, spray cone angle and spray area were considered and evaluated under the change of injection pressure, ambient gas density and injection duration with assurance boundary conditions for all experiment cases. The injection pressure affecting the reduction of the spray cone angle was found when being increased from 40 MPa to 100 MPa. In addition, raising the ambient gas density reduces the spray length of the fuels at the same time and slows down the speed at which spray impinges on the wall. Typically in the case of GB40 at pressures of 100 Mpa and 1500 μs, corresponding to ambient gas density levels from 10-20-30 kg/m3, the penetration rate is 100, 62.5, 47.61 m/s, respectively. Meanwhile, at a pressure of 40 Mpa, with the same conditions, the speed of hitting the wall is 58.82, 42, 40 m/s, respectively. The results clearly show the influence of ambient gas density on the spray formation rate and stability when increasing injection pressure. The fuels had different biodiesel compositions from 10, 20 and 40 % by volume to indicate differences in the viscosity properties of the fuels. In addition, the association between the properties makes the difference in the results of the spray area during the test. Optical modeling was set up according to the shadowgraph method using high-speed cameras to collect images from the spraying process. The method applies an image processing algorithm in MATLAB to analyze the images after the experiment. Overall evaluation of the spray characterization process, the physical properties as well as the theoretical models are reviewed, providing an overview for the study of the bio-fuel mixture to apply to GCI engines with the advantage of longer ignition delay.