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DIESEL SPRAY CHARACTERISTICS AND ITS COMBUSTION
Masataka ARAI 한국자동차공학회 2005 한국자동차공학회 Workshop Vol.2005 No.-
Spray formation mechanism of a diesel spray and its combustion process were reviewed. Spray formation mechanism of the diesel spray was controlled by a cavitation inside an injection nozzle. The Sauter mean diameter of a diesel spray became small when the cavitation occurred in the nozzle and it resulted in a complete spray. The empirical equations of the Sauter mean diameter were shown with the discussion of the cavitation. The spray tip penetrations of free and wall impingement sprays were introduced with the equations. The spray tip penetration was discussed with air entrainment process. Impingement spray was discussed with penetration and adhering fuel on the wall. High pressure injection spray was introduced with its spray characteristics. Spray-to spray interaction was clearly shown by many photographs to propose a new spray system. Evaporation process on an impingement wall was duscused. Ignition delay and the empirical equations of it were reviewed. The ignition delay was greatly affected by the spray movement and surrounding conditions. Wall and residual gas effects on the ignition delay were reviewed. The OH flame kernel and hot flame kernel observed at the ignition of impingement spray were explained. Alos, effect of injection pressure and effect of wall impingement on flame development process was explained.
( Masataka Arai ),( Akira Ishii ),( Masahiro Saito ) 한국액체미립화학회 2005 한국액체미립화학회 학술강연회 논문집 Vol.2005 No.-
Atomization behavior of a single droplet impinged on surface oscillating with ultra-sonic frequency of 20 kHz was investigated as a new method of fine-spray formation. Distilled water, ethanol and 50-80wt% glycerin solution were used as the test liquids to find the effects of viscosity and surface tension on ultra-sonic atomization. The amplitude of oscillation A and the droplet volume Vd were changed between A =25-125μm, Vd = 4-20 mm3 respectively. As the result, it was found that a fine spray was formed after the droplet impingement when the amplitude was smaller than A =50μm, while ligament and large droplets were formed at larger amplitude than A =50μm. The SMD of the spray after impingement was about D32=70μm when the amplitude was small, but the SMD became large with increase of the amplitude. Also, at low amplitude of A =25μm, the surface energy of spray after impingement increased remarkably compared with that of droplet before impingement. On the contrary, at amplitude of A >50μm, the kinetic energy after impingement has exceeded the surface energy. Namely, the oscillation energy was acted for rebounding of droplet rather than the atomization of droplet. The atomization efficiency decreased exponentially with increasing the amplitude of oscillation independent of the physical properties of test liquids. Thus, the low amplitude of oscillation could allow fine atomization by the disintegration of liquid film after the droplet impingement.
Design of Gesture Interface for Deskwork Support System
Masataka Nishino,Yuto Nakanishi,Masao Sugi,Yewguan Soo,Jun Ota,Tamio Arai 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
We have proposed the attentive workbench (AWB), which helps workers to perform tasks at their desksfrom both informational and physical sides. In this report, we propose a method for constructing pointing gesture-basedinput interface in AWB in the view of usability. The usability is evaluated by the necessary time for users toaccomplish deskwork tasks.
Behavior of GDI fuel spray adhered on a wall
( Kengo Jinnai ),( Yoshihiro Kobayashi ),( Masataka Arai ) 한국액체미립화학회 2017 한국액체미립화학회 학술강연회 논문집 Vol.2017 No.-
Impingement behavior of iso-octane spray injected from GDI nozzle was investigated. Ground glass plate was used as an impingement wall to observe trace-mark of liquid film on the wall. When fuel spray adhered on the ground glass plate, the light transmitted only through adhesion area of liquid fuel. This light-transmitted liquid film area was observed from bottom side of the impingement plate. The trace-mark image of liquid film was taken by high-speed camera during and after injection period. It was binarized and evaluated as the adhered area of liquid film. Adhesion area was measured under two injection pressure conditions (P<sub>inj</sub>=0.6MPa and 3.0MPa) and two impingement distances (z= 30 mm and 50 mm) with dry wall and wet wall conditions. The total injection period was 15 ms for single shot injection. As for the split injection (10ms x 3 shots), interval of split injection was 5ms but total injected mass was kept to be same as the single injection. Fuel adhesion started when spray tip arrived at the impingement plate, its area expanded with injection elapsed however it was always narrower than the wall spray area that was observed as a general top view image of impingement spray. Further, adhesion area still increased during a few milli-seconds after injection finished. During the interval period of split injection, adhesion area was also expanded. Adhesion area on wet wall was narrower than that on dry wall because of secondary splash from wet wall. Since the continuous increase of adhesion area during the interval period was cancelled by the splash caused by following split spray, there was no apparent difference on adhesion film behaviors of single and split fuel injection. Larger increase rate of adhesion area was obtained at P<sub>inj</sub>=3.0MPa than that at P<sub>inj</sub>=0.6MPa, but qualitative behavior of adhesion area was not affected by the injection pressure.