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In developing a direct injection gasoline engine, the in-cylinder fuel air mixing is key to good performance and emissions. High speed visualization in an optically accessible single cylinder engine for direct injection gasoline engine applications is an effective tool to reveal the fuel spray pattern effect on mixture formation The fuel injectors in this study employ the unique multi-hole turbulence nozzles in a PFI-like (Port Fuel Injection) fuel system architecture specifically developed as a Low Pressure Direct Injection (LPDI) fuel injection system. In this study, three injector sprays with a narrow 40° spray angle, a 60°spray angle with 5°offset angle, and a wide 80° spray angle with 10° offset angle were evaluated. Image processing algorithms were developed to analyze the nature of in-cylinder fuel-air mixing and the extent of fuel spray impingement on the cylinder wall.

In-cylinder flows in four-valve SI engines were examined by high frame rate flow visualization and two-component LDV measurement. It is believed that the tumble and swirl motion generated during intake breaks down into small-scale turbulence later in the cycle. The exact nature of this relationship is not well known. However, control of the turbulence offers control of the combustion process. To develop a better physical understanding of the in-cylinder flow, the effects of the cylinder head intake port configuration and the piston geometry were examined. For the present study, a 3.5L, four-valve engine was modified to be mounted on an AVL single cylinder research engine type 520. A quartz cylinder was fabricated for optical access to the in-cylinder flow. Piston rings were replaced by Rulon-LD rings. A Rulon-LD ring is advantageous for the optical access as it requires no lubrication.

The requirement of reduced emissions and improved fuel economy led the introduction of direct-injection (DI) spark-ignited (SI) engines. Dual-fuel injection system (direct-injection and port-fuel-injection (PFI)) was also used to improve engine performance at high load and speed. Ethanol is one of the several alternative transportation fuels considered for replacing fossil fuels such as gasoline and diesel. Ethanol offers high octane quality but with lower energy density than fossil fuels. This paper presents the combustion characteristics of a single cylinder dual-fuel injection SI engine with the following fueling cases: a) gasoline for PFI and DI, b) PFI gasoline and DI ethanol, and c) PFI ethanol and DI gasoline. For this study, the DI fueling portion varied from 0 to 100 percentage of the total fueling over different engine operational conditions while the engine air-to-fuel ratio remained at a constant level.

Internal flow characteristics of a close coupled catalytic converter were examined by LDV measurements and high speed flow visualization. Although previous studies have been done on catalytic converters, they were conducted at steady state and using water flow seeded with a small quantity of tracer particles. The purpose of this study was to develop a better understanding of dynamic flows inside catalytic converters. The high speed flow visualization films and LDV results showed that areas of separation and circulation were present in the inlet region of the converter. Backflows into the neck of the converter were also observed. Each cylinder exhausted into a different region of the converter, with the front-middle region having the heaviest amount of flow. Large bursts of flow were created by each cylinder, while other regions of the inlet region showed backflows or very low flow rates. The midsection of the converter had a more uniform overall flow pattern.

Electro-pneumatic valve actuators are used to eliminate the cam shaft of a traditional internal combustion engine. They are used to control the opening timing, duration, and lift of both intake and exhaust valves. A physics based nonlinear mathematical model called the level one model was built using Newton's law, mass conservation and thermodynamic principles. A control oriented model, the level two model, was created by partially linearizing the level one model for model reference parameter identification. This model reduces computational throughput and enables real-time implementation. A model reference adaptive control system was used to identify the nonlinear parameters that were needed for generating a feedforward control signal. The closed-loop valve lift tracking, valve opening and closing timing control strategies were proposed.

Improvements in engine combustion depend on a thorough understanding of the actual in-cylinder flows. This study is thought to be the first fully three-dimensional (3-D) LDV measurement effort that evaluated the vast majority of the displacement volume under a variation of speed, load, and stroke during the intake and compression strokes. The intake port geometry was not changed during the course of the study. Most of the engine setups studied showed similar in-cylinder velocity patterns. The well developed tumble motion exhibited only marginal changes under the different speed, load, and throttle conditions with one exception: at idle condition, the tumble motion broke down into two equally strong downward flows along the cylinder liner. For all the other setups a robust tumble motion, which was distributed throughout the displacement volume prevailed until the end of measurement, sustaining significant amounts of ttumble motion until late in compression.

The existence of the cyclic variation of the flow inside an cylinder affects the performance of the engine. Developing methods to understand and control in-cylinder flow has been a goal of engine designers for nearly 100 years. In this paper, passive control of the intake flow of a 3.5-liter DaimlerChrysler engine was examined using a unique optical diagnostic technique: Molecular Tagging Velocimetry (MTV), which has been developed at Michigan State University. Probability density functions (PDFs) of the normalized circulation are calculated from instantaneous planar velocity measurements to quantify gas motion within a cylinder. Emphasis of this work is examination of methods that quantify the cyclic variability of the flow. In addition, the turbulent kinetic energy (TKE) of the flow on the tumble and swirl plane is calculated and compared to the PDF circulation results.