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A two-dimensional Laser Induced Fluorescence (LIF) system was developed to visualize the oil distribution and study the oil transport in the piston ring pack of a single-cylinder diesel engine through an optical window on the liner. The system gives high spatial and intensity resolutions so that detailed oil distribution on the piston as well as between the rings and the liner can be studied. This work primarily focused on investigating different oil transport mechanisms on piston crown land and second land under various engine operating conditions. Oil accumulation on the crown land was observed under certain operating conditions and top ring up-scraping was deemed to be the source for this oil accumulation. Two mechanisms for the oil flow on the second land were identified, namely, inertia driven oil flow in the axial direction and oil dragging by gas flow in the circumferential direction. Finally, the effects of ring rotation were investigated.

The oil control ring is the most critical component for oil consumption and friction from the piston system in internal combustion engines. Three-piece oil control rings are widely used in Spark Ignition (SI) engines. However, the dynamics and lubrication of three piece oil control rings have not been thoroughly studied from the theoretical point of view. In this work, a model was developed to predict side sealing, bore sealing, friction, and asperity contact between rails and groove as well as between rails and the liner in a Three Piece Oil Control Ring (TPOCR). The model couples the axial and twist dynamics of the two rails of TPOCR and the lubrication between two rails and the cylinder bore. Detailed rail/groove and rail/liner interactions were considered. The pressure distribution from oil squeezing and asperity contact between the flanks of the rails and the groove were both considered for rail/groove interaction.

Engine oil consumption is one of the primary interests for the automotive industry in controlling emissions and reducing service cost. Due to a lack of understanding of the mechanisms of oil transport along the piston, reducing oil consumption from the ring pack of internal combustion engines has been extremely challenging for engine manufacturers and suppliers. Consequently, a thorough experimental characterization of oil transport processes is critical to 1) reduce lead-time and cost of new piston ring pack development, 2) provide the physically based oil transport models needed to develop analytical tools for oil consumption prediction. In this work, a two-dimensional multiple-dye Laser-Induced Fluorescence (LIF) visualization system was successfully implemented in a diesel and a spark-ignition engine.

The paper presents a detailed study of a unique lubricating oil transport and exchange path that is important for friction, wear, and oil consumption in a 4 stroke spark ignition engine, namely the oil flow from the piston to the cylinder liner. The study consisted of experiments with a test engine utilizing 2D LIF (Two Dimensional Laser Induced Fluorescence) techniques to view real time oil transport and exchange, along with computer modeling. The effects of engine speed, load, and oil ring design were included as part of the research. The test conditions ranged from 800 RPM to 4500 RPM, while the load was varied from closed throttle to wide open throttle. Several different oil control ring designs were utilized, including U-Flex, Twin-Land, and 3-Piece. Oil transport and exchange from the piston to the liner was observed under several different engine conditions, typically moderate to high engine speeds and low loads.

An experimental study was carried out that qualitatively examined the mixture preparation process in port fuel injected engines. The primary variables in this study were intake valve lift, intake valve timing, injector spray quality, and injection timing. A special visualization engine was used to obtain high-speed videos of the fuel-air mixture flowing through the intake valve, as well as the wetting of the intake valve and head in the combustion chamber. Additionally, videos were taken from within the intake port using a borescope to examine liquid fuel distribution in the port. Finally, a simulation study was carried out in order to understand how the various combinations of intake valve lifts and timings affect the flow velocity through the intake valve gap to aid in the interpretation of the videos.