Yuzo Aoyagi

APPLICATION OF LASER DOPPLER ANEMOMETRY TO A MOTORED DIESEL ENGINE

Some problems associated with applying laser doppler anemometry to the measurement of air motion in the cylinder are discussed from experiments using both forward and back scattering techniques in a motored diesel engine. The effects of doppler broadening caused by the velocity gradient and the diameters of the scattering particles are examined. The decaying process and the structure of the in-cylinder flow field are discussed in terms of measurements of the main flow velocity, the turbulence intensity, and the macro time scale and normalized power spectrum of the turbulence. Forward and back scattering measurement results are compared.

Super clean diesel by usage of wide range, high boosted and cooled EGR system in single cylinder engine – Japanese national project: super clean diesel engine

The heavy duty diesel engines have achieved status as prime movers for CO2 emissions. However, in the future heavy duty diesel engines will be required to have lower NOx and particulate matter (PM) emission levels than today. In this study high boost and lean diesel combustion has been attempted by a single cylinder engine in order to obtain a good engine performance and clean exhaust emission. The experiment has been done with intake air quantity up to five times of a naturally aspirated (NA) engine and 200MPa injection pressure. The adopted pressure booster is an external supercharger; and this experimental system can control the intake air temperature and also produce a high exhaust gas recirculation (EGR) rate in a wide speed and high load range.

Visualized analysis of diesel combustion under the high boosting engine condition

TDC 1 2 5 10 15 20 30 Fig. 2. High-speed photographs of diesel combustion ( Pinj = 100 MPa, = 3.5, = 16, Ne = 1000 rpm ). Experimental results of High boosting combustion The pressure diagrams and the rates of heat release are shown in Fig. 1, when the boost pressure increased. Figure 2 shows the combustion photographs under the conditions, which are approximately 3.5 times intake air of NA engine, the air excess ratio = 3.5 constant, the nozzle specification 0.17×6 and the injection pressure Pb=100MPa. The high boosting gives good combustion and high thermal efficiency. It is very difficult to take combustion photo in a diesel engine due to high cylinder pressure but we success in 15MPa such as high cylinder pressure. 0.4

Premixed Lean Diesel Combustion Charasteristics on Supercharged Diesel Engine

Recently, pre-mixed lean mixture combustion has attracted attention, and many researchers are investigating compression ignition of a pre-mixed lean mixture. Previous research in our laboratory has shown that low NOx emission combustion is obtained by PREDIC (PREmixed lean DIese1 Combustion). However some problems still remain, such as higher fuel consumption, a lack of ignition timing control, a large increase in THC and CO, compared to conventional diesel combustion. The output limit of PREDIC is about 50% of conventional diesel combustion. So in order to increase the PREDIC engine output, supercharging was adopted. It was resulted that the power output was higher and the fuel consumption was better than the conventional natural aspiration diesel engine using supercharging. The numerical simulation analysis shows that NOx was produced at rich mixture area because of lower spray penetration under high density conditions. As the result, the high injection rate is effective to make a lean mixture.