An Analysis of Diesel Fuel Spray Characteristics with Higher Injection Pressure

Akihiro Kita･Ryotaro Seto･Tokuji Kuronita･Yoshiaki Nishijima (Aichi Institute of Technology)

Higher injection pressure is one way to improve exhaust performance on diesel engines. In a constant volume vessel, the momentum transition of diesel fuel spray from the nozzle was measured, and the injection velocity was calculated. The injection pressure condition was up to 400MPa. The injection velocity was also measured by observing spray penetration using a high-speed camera.

A Study of Exhaust Performance Improvement with Higher Injection Pressure

Ryotaro Seto･Akihiro Kita･Takaya Goto･Tokuji Kuronita･Yoshiaki Nishijima (Aichi Institute of Technology)

Higher pressure injection on diesel engines contributes to increasing spray momentum and improving spray atomization. Higher momentum and fine atomization promote fuel-air mixing resulting in soot reduction.
To verify the estimated mechanism of soot reduction, we measured exhaust gas characteristics by combustion tests using a single-cylinder engine. Actual measurement results show soot reduction with fuel injection pressure increasing up to 400MPa.

Evaluation of High Compression Ratio Achieved by Extending the Stroke Length on Heavy Duty Diesel Engine

Hiroaki Saito･Munemasa Hashimoto･Yoshinori Ishii･Hisashi Ozawa (Isuzu Advanced Engineering Center)

When the compression ratio is increased to improve thermal efficiency, deterioration of combustion and increase of heat loss are inevitable by reducing volume of combustion chamber, and the improvement of thermal efficiency is extremely small. In this study, the compression ratio was increased by extending the stroke length without changing the combustion chamber of piston by using a single-cylinder test engine. As a result, under the condition of equivalent excess air ratio, it was confirmed that the effect of improving indicated thermal efficiency was higher than reducing volume of combustion chamber without deterioration in combustion.

Study of Combustion Improvement by Ridge Shape for Spray Splitting

Kazunori Yoshitomi･Mori Ishii (Hino Motors)

This study provides a concept that improves the mixing of air into the fuel spray by applying a ridge-shape to the combustion chamber which splits the spray into two directions.
The shape was finalized from CFD calculations and heat release rate profiles experimentally obtained from single-cylinder engine bench test.
Improvement in thermal efficiency and reduction in smoke emissions were displayed, which is thought to be due to the splitting of the spray which increases the homogeneity of air-fuel mixture.

Effect of Operating Conditions and Fuel Properties on Nanostructure of Soot Particles from Diesel Engine

Yu Kuroshima･Mizuki Obara･Kazuki Inaba･Kazuhiro Hayashida (Kitami Institute of Technology)

The effects of operating conditions and fuel properties on the carbon crystallite size of soot particles in a single-cylinder diesel engine were investigated. The results showed that the carbon crystallite size increased with increasing high temperature residence time as the operating conditions were changed, regardless of fuel properties. And the carbon crystallite size with low aromatic content fuels was smaller than with the diesel fuel.