this chamber, the condition of pc = 100 kPa seems to produce better distribution of the mixture than the cases of pc = 150 and 200 kPa.
Figure 3.1.4.2: Effects of ambient denity on (a) mixture formation and flame development, (b) heat release and flame pattern
Fig.3.1.4.2 (b) shows heat release rate dQ/dt together with nozzle needle lift NL against time. According to the figure, increasing ambient density produces high heat capacity at spray boundary reflects shortens ignition delay and earlier rise of heat release rate. However, at high ambient density, increasing rate of initial heat release is gentle and combustion duration becomes long as compared with lower ambient density condition. In addition, heat release pattern related with the changes of flame pattern, are compared within the same of time at all conditions. As result, the mixture formation process may affect heat release history and flame pattern as well.
3.2 Summary
It is seen from the schlieren images that high ambient density weakens the spray penetration. The spray path is bended by the swirl motion. High ambient density resulting from the increasing of boost pressure is anticipated to influence the mixture formation during ignition delay period and burning process. As seen from the flame images, tendencies of flame distribution well correspond to the distribution of combustible mixture observed in schelieren images. This result indicates that the intensity of flame pattern is a kind of signal that tells the position