In diesel engines, late combustion is a cause of degradation in thermal efficiency. Late combustion is caused by a high-equivalent ratio region that exists at the tip of the diesel spray flame after the end of fuel injection, and it may be possible to reduce late combustion with an improvement in air utilization. In this study, the effect of the interaction between the diesel spray and objects to reduce late combustion under various ambient conditions and fuel injection pressures was investigated using a constant volume vessel. The experimental results showed that regardless of ambient oxygen concentration and fuel injection pressures, objects with the shape of a triangular prism and a cone can split the spray flame, resulting in a reduction in late combustion due to an improvement in the air utilization.
Isogai et al. (Wed,) studied this question.