1996-05-01

Combustion Observation of OSKA-DH Diesel Engine by High-Speed Photography and Video System 961159

The OSKA-DH diesel engine employed a unique system (hereafter called OSKA system) which is composed of a single-hole fuel injector, an impinging disk and a re-entrant type combustion chamber.
This study is concerned with the combustion observation of both OSKA-DH diesel engine and conventional DI diesel engine by the high-speed photography and video system. This video system enables us to take combustion photographs under the warm-up condition of the engine.
From the observation of those photographs, the OSKA-DH engine shows the shorter ignition delay compared with a DI diesel engine and the combustion flame of OSKA-DH diesel engine are concentrated in the center of the combustion chamber and a relatively monotonous flame intensity are observed.
THE AUTHORS HAVE DEVELOPED a new type of Direct Injection Stratified Charge Engine called “Direct Fuel Injection Impingement Diffusion Stratified Charge System” (hereafter called OSKA System).
The authors have already reported the performance and exhaust emission of the methanol, gasoline and diesel engines utilizing this OSKA System (1), (2), (3), (4), (5), (6), (7), (8), (9), (10) and (11)*.
In the previous reports (8), (9), (11), the observation of impinged fuel spray onto the impinging disk was studied by using the pressurized vessel and bottom view and side view photographs were taken at the same time. And the high-speed combustion photographs were taken for both bottom view and side view by using an experimental transparent engine. The radial diffusion of fuel spray showed almost same tendency between the pressurized vessel and transparent engine. But the axial diffusion of fuel spray showed the different tendency.
The high-speed photographs brought general information of mixture formation and combustion. But the high-speed camera must be start before the fuel injection start. So, the temperature condition in the cylinder are not completely same as continuous operation condition.
In this report, the video system with a flash light illumination was used to observe the impinged fuel spray and the combustion flame of the OSKA-DH diesel engine. This video system enables us to observe the combustion chamber under warm-up condition of the engine. For reference, the combustion flame of a conventional DI diesel engine was observed by the same video system without a flashlight illumination.
The engine design parameters such as the combustion chamber configuration, compression ratio and so on were kept the same as the performance test engine. As the fuel spray diffusion and combustion are significantly affected by the engine operating conditions, it is very important to maintain exactly the same operating conditions as the performance test.
The observation of high-speed photography and video system are compared.

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