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A CFD Investigation into the Effects of Intake Valves Events on Airflow Characteristics in a Motored 4-Valve Engine Cylinder with Negative Valve Overlapping
Technical Paper
2007-24-0032
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
This paper presents a computational study of the airflow features within a motored 4-valve direct injection engine cylinder. An unconventional intake valve strategy was investigated; whereby each valve on the pair of intake valves was assumed to be actuated with different lifts and duration. One of the intake valves was assumed to follow a high-lift long duration valve-lift profile while the other was assumed to follow a low-lift short duration valve-lift profile. The pair of exhaust valves was assumed to be actuated with two identical low-lift short duration valve-lift profiles in order to generate the so-called negative valve overlapping (NVO). The in-cylinder flow fields developed with such intake valve strategy were compared to those produced in the same engine cylinder but with the application of identical low-lift short duration intake valve events. The computational results of such an approach showed a considerable modification of the intake generated cylinder-averaged swirl and tumble motions. Besides, utilizing this intake valve strategy with a difference in phase between timings of the high-lift and low-lift intake valves revealed an enhancement in the induction-produced turbulence characteristics. Applying such intake valve strategy in real-life 4-valve engines is expected to improve the combustion aspects of both spark ignition (SI) and homogeneous charge compression ignition (HCCI) combustion systems.
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Mahrous, A., Wyszynski, M., Xu, H., Tsolakis, A. et al., "A CFD Investigation into the Effects of Intake Valves Events on Airflow Characteristics in a Motored 4-Valve Engine Cylinder with Negative Valve Overlapping," SAE Technical Paper 2007-24-0032, 2007, https://doi.org/10.4271/2007-24-0032.Also In
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