In terms of the global environment problems, emission regulation which is for Particulate Matters (PM) has been getting severe. One of the root causes of PM is a fuel wetting which is adhered on an engine wall such as an intake port and a combustion chamber. Therefore, it is useful to investigate the fuel wetting behaviors from formation on the wall to evaporation process.
In this study, the new method which analyzes the fuel wetting by using infrared absorption is proposed. The feature is that it is possible to measure the fuel wetting without additive by using the infrared absorption characteristics of fuel itself, which is the increasing tendency of the absorbance as the liquid film thickness increases for infrared wavelength 3.4μm. Therefore, the relationship between formation and evaporation of the fuel wetting and the mechanism of formation which evaporate earlier can be clarified by using this new method.
Experimentally, it was demonstrated that the thickness of the fuel wetting with an accuracy of ±2μm and the time series charge of its could be measured in the range of ~50μm. In addition, it was verified that the volume decrease exponentially with elapsed time and that the time required for evaporation completed decrease nonlinearly with wall temperature increasing. Furthermore, it was investigated that high fuel pressure is effective as a mean for reducing fuel wetting and evaporating it earlier.
From these results, this new method can contribute considerably to develop the fuel spray which reduce the volume of the fuel wetting and evaporate it earlier.