CFD Simulation and Optical Engine Diagnostics of Mixture Formation Processes in DI Gasoline Engine with Flexible Valvetr
The interactions of multi-hole direct injection (DI) gasoline sprays with the charge motion are investigated using computational fluid dynamics simulation and high-speed imaging of sprays inside engines. Advanced flexible valve-train, with valve-deactivat
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Abstract The interactions of multi-hole direct injection (DI) gasoline sprays with the charge motion are investigated using computational fluid dynamics simulation and high-speed imaging of sprays inside engines. Advanced flexible valve-train, with valve-deactivation and variable valve-lift, produces very dynamic charge flow motions, with varying tumble and swirl ratios. The resultant turbulent flow interact with off-axis multiple-hole DI injections, has important implications for the engine mixing and resultant combustion performance. The effects of injection timing on the bulk flow motion and fuel–air mixing in an optical accessible engine, in terms of tumble and swirl ratios, turbulence, and fuel wall film behaviors are first discussed for the conventional baseline engine geometry. The early- and latevariable intake valve closing events are then tested in a metal engine. The effects of different valve lifts and valve deactivation on the mixing and combustion are then discussed. Using integral analyses of the simulation results, the mechanisms in reducing fuel consumption and emissions in a variable valve-actuation engine, fuelled by side-mounted multi-hole DI injectors are illustrated. The implications to the engine mixing and the resultant combustion in a metal engine are demonstrated. Keywords Direct injection engine
Gasoline engine Flexible valve CFD Optical
F2012-A05-011 Y. Zheng (&) P.-I. Lee A. Matsumoto X. Xie M.-C. Lai Wayne State University, Detroit, MI, USA e-mail: [email protected]
SAE-China and FISITA (eds.), Proceedings of the FISITA 2012 World Automotive Congress, Lecture Notes in Electrical Engineering 190, DOI: 10.1007/978-3-642-33750-5_4, Ó Springer-Verlag Berlin Heidelberg 2013
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1 Introduction Advanced valvetrain coupled with Direct Injection (DI) provides an opportunity to simultaneously reduce fuel consumption and emissions [1]. Because of their robustness and cost performance, multi-hole nozzles are currently being adopted as the gasoline DI fuel injector of choice, mostly in the side-mount configuration. In addition, ethanol and ethanol-gasoline blends are being used in the down-sized, down-speed and variable-valve-train engine architecture, because of their synergy in improving the turbo-charged DI gasoline performance. There has been much research in the literature carried out with interactions of DI gasoline sprays and the in-cylinder flow fields [2–10], but very little study on the side-mounted multi-hole nozzle with the interaction of charge motions, which is the focus of the current study. Multi-dimensional computational fluid dynamics (CFD) offers a promising alternative to experiments for its capability to offer much more detailed information on in-cylinder mixture formation. Numerical method has been used to analyze the injector nozzle flow, near-field primary spray evolution, and wall impingement of gasoline and diesel engine, and compare with experimental observation [11–15]. The charge motion and its interaction with spray were studie
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