Tatsuo Takaishi

Direct water injection to improve diesel spray combustion

Now, it is essential to apply some measures for NOx reduction to low-speed diesel engines emitting much more NOx than high-speed engines. At the same time PM emission must be reduced especially when bunker fuel or heavy fuel is burned. This paper describes the applications of SFWI (Stratified Fuel Water Injection) system and DWI (Direct Water Injection) system to large sized diesel engines to reduce NOx and PM emission. SFWI system makes it possible to inject water during fuel injection from the same nozzle hole without mixing the liquids. DWI system injects water with high injection pressure from the other injection hole than the fuel injection hole into the combustion chamber directly. For testing both the systems, a 2-stroke-cycle low-speed test engine was used.Copyright

Verbrennungseigenschaften von Dumbbell-Schweröl

In jungster Zeit wird ein Kraftstoff niedriger Qualitat mit ungewohnlicher Verteilung der Destillat-Temperaturen und hohem Gehalt an aromatischen Hydrokarbonaten von Hafen zur Verfugung gestellt und hat teilweise schon zu Beschadigungen in Schiffsdieselmotoren gefuhrt. Im vorliegenden Bericht der Universitat Kyushu, Japan, werden die Verbrennungseigenschaften solcher Kraftstoffe mit Hilfe verschiedener Einrichtungen, unter anderem einem Transparent-Motor, naher untersucht. Unter Berucksichtigung der aus Experimenten und Simulation der Einspritzeigenschaften gewonnenen Erkenntnisse wird ein neues Einspritzsystem fur derartige Kraftstoffe niederer Qualitat vorgestellt.

Prediction Calculation of the Cavitation Erosion Generated in Connection With a High-Pressure Jet

High-pressure jets are being pursued in diesel engines in order to facilitate development of next-generation fuel injection systems aiming at high performance, high fuel economy, and low emissions of smoke. Cavitation erosion accompanying the use of high-pressure jets for diesel fuel injection pumps is a factor responsible for reduced equipment durability and performance. In response, the project reported here involved the production of test equipment for the purpose of replicating the behavior of a fuel injection pump as it would occur in an actual diesel engine, with erosion testing, and analysis of the shock pressure by the cavitation, and its generating part. As a result, the following behaviors were noted. (1) In the 3-dimensional analysis of an unsteady cavitation jet stream, the shock pressure by the cavitation and its generating part can be predicted. (2) If the exit clearance of a hole is adjusted, the generating position of a erosion is controllable.Copyright

Prediction of cavitation erosion in diesel engine fuel injection systems

A new system developed by the authors to predict the cavitation erosion of the fuel injection system utilizes ultrasonic wave issued by collapse of cavities in the system. This prediction system can replace the conventional time-consuming endurance test and thus greatly contributes to the saving of cost and time. The technical features of this system include: (1) Detection of ultrasonic wave through the fuel injection pipe wall using a piezoelectric sensor, with the ultrasonic wave signal intensity in a higher frequency range increasing with the cavitation intensity, i.e., the level of energy released by the collapse of cavities; (2) the system output representing effective cavitation intensity which is given after being processed from the raw state in a high pass filter; and (3) capability of dealing with a higher level of accuracy than by the conventional method.