Here, the straight and equal intensity of light is produced by the Xe-light source. Then, the parallel light of Xe light created by concave mirror was reflected by the mirror surface. A ring edge with a diameter of 2.5 mm was used as a schlieren stop and was set at the focal point of another concave mirror. The atmosphere was filled by nitrogen gas in the case of schlieren photography.

Effects of ambient density

Fig.5(a) shows the schematic diagram of a free-piston type rapid compression machine which used tosimulate actual phenomenon inside the combustion chamber and the basics specifications are listed in Table 3.1.4.1:  

Table 3.1.4.1: Experimntal conditions

The charging pressure pc were changed to pc =100 kPa, 150 kPa and 200 kPa with keeping ambient temperature of Ti = 850 K. At every condition, ambient density ρ was ρ =16.6 kg/m3, 25.0 kg/m3, 33.3 kg/m3, respectively. Schlieren photograph indicated the detail of mixture formation was resulting from non-combustion diesel sprays which avoided by using nitrogen ambient and the direct photography technique is used to capture the flame development images, as shown in Fig.3.1.4.1 (b).