Characteristics of Flat-Wall Impinging Spray Flame and Its Heat Transfer under Small Diesel Engine-Like Condition. 3th Report: Effect of Oxygen Concentration

To investigated heat transfer phenomena inside the combustion chamber wall in diesel engines, we investigated the effects of spray/flame impingement on transient heat flux to the wall. By using a constant volume vessel under engine-like condition, surface heat flux of the wall at spray/flame impingement was measured with three thin film thermocouple heat flux sensors. Fuel was injected using a single-hole injector with a 0.133 mm diameter nozzle. Under these conditions, spray evaporates, then burns near the wall. In order to investigate the relation between diesel flame and wall heat loss, two colour-method was applied to observe local flame temperature distribution. The effect of oxygen concentration on the heat transfer was investigated parametrically. The results showed that the ratio of oxygen concentration influenced the combustion behaviour, which has significant effect on flame temperature and flame contact area that gave rise to further heat loss on the wall.