Experimental Investigation on Fuel Spray Optimization in Gasoline Direct Injection Engine
Optical Visualization system was applied to record images of the processes of spray, mixed gas formation and combustion in a homogenous GDI engine. Fuel spray was optimized by visual analysis of the images, thus improved the quality of mixed gas and combu
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Abstact Optical Visualization system was applied to record images of the processes of spray, mixed gas formation and combustion in a homogenous GDI engine. Fuel spray was optimized by visual analysis of the images, thus improved the quality of mixed gas and combustion in the cylinder, it can provide the reference for injector selection and EMS calibration. Keywords Endoscope
Spray GDI Heat release rate Wetting
Definitions/abbreviations K Relative air-to-fuel ratio WOT Wide open throttle SOI Start of injection MFB Mass fraction burned CA Crank angle BSFC Brake specific fuel consumption IMEP Indicative mean effective pressure
F2012-A01-006 B. Jiang (&) X. Pan F. Liu C. Wang X. Feng Changan Auto Global R&D Center of Changan Automobile Co LTD, Beijing, China e-mail: [email protected]
SAE-China and FISITA (eds.), Proceedings of the FISITA 2012 World Automotive Congress, Lecture Notes in Electrical Engineering 189, DOI: 10.1007/978-3-642-33841-0_3, Springer-Verlag Berlin Heidelberg 2013
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1 Introduction In the recent years, as fuel consumption and emissions control regulations become more severe, improvement in fuel efficiency and reduction in exhaust emissions are the main goals. The concept of turbocharged downsized engine has the potential to achieve such goals. Compared with PFI engine, fuel–air mixture preparation is in the cylinder in GDI engine, fuel vaporizes to drop the gas temperature, and that the mixed gas stays less time in the cylinder therefore knock tendency is down, this is the advantage of GDI engine to apply turbocharged technology. Furthermore, compared with homogenous charge mode, layered lean charge mode has disadvantages in emission control and combustion stability, and that the quality of domestic gasoline restricts extend of layered lean mode GDI. Overall, homogenous GDI engine becomes the trend of domestic gasoline now. Intake port of the conventional PFI engine is like a preparative volatilization chamber, it increases the time of fuel evaporation. For fuel directly inject in the combustion chamber in GDI engine, the time of fuel vaporization is so short that it is difficult to form homogenous mixed gas, and that fuel direct injection may engender wall wetting. It makes the rich gas around burn incompletely, thereby solid particle and HC emissions increase. If wetting is excessive, it would also affect fuel consumption and oil dilution badly.
2 Experimental Study The engine used in the present work is shown as Table 1. Figures 1 and 2 show the spray images of selected Delphi 6 holes injector, it shows with 50 and 100 bar rail pressure slightly separated streams. Spray penetration with 150 bar compared to 100 bar results in more droplets with smaller sizes. AVL Visioscope system was applied in the experimental study. At first, endoscope and light guide was installed for optical access to the combustion chamber, and record of engine synchronized images of spray, mixed gas formation and combustion on crank angle base by a camera, then post-process a
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