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The trends in the development of spark ignition engines leads to the adoption of lean mixtures in the combustion chamber. Torch ignition systems have potential to reduce simultaneously the NOx and CO emissions, while keeping the fuel conversion efficiency at a high level. This study aims to design and analyze a torch ignition system running with ethanol on lean homogeneous charge, adapted to an Otto cycle single-cylinder engine with optical visualization. The main objective is to achieve combustion stability under lean burn operation and to expand the flammability limit for increasing engine efficiency by means of redesigning the ignition system adapting a pre-chamber to the main combustion chamber. Experiments were conducted at constant speed (1000 rpm) using ethanol (E100) as fuel, for a wide range of injection, ignition and mixture formation parameters. Specific fuel consumption and combustion stability were evaluated at each excess air ratio.

This study concerns the sprays produced by a single hole direct injection injector through a systematic image treatment methodology. The images were obtained by high speed recording associated with shadowgraph technique. The recording frequency was 6504 Hz. Grayscale images were obtained after a process of histogram adjusting and image subtraction. The spray volume and penetration was evaluated through a process of edge detection in the hollow cone of the spray injection. A criterion based on pixel values was taken to localize the spray edges as angles and x and y position data. The high pixel values were associated with liquid phase while the low pixel values were associated to its absence. Computational codes written in Matlab environment were used to analyze the numerical matrices associated to the images. The high frequency image recording allowed studying the sprays in all its development. The tests were conducted with injection pressure variation.

In this paper, particle image velocimetry (PIV) and computational fluid dynamics (CFD) were employed to a qualitatively and quantitatively study in the behavior of the intake-generated steady flow in a four valve spark ignition single cylinder research engine. Steady flow experimental characterization was made for different intake valve lift values. PIV was used to investigate the flow pattern generated within the engine cylinder. The measurements were taken in the symmetry vertical plane between the inlet and outlet valves. These same conditions were modeled using Star-CCM+ commercial package. The CFD model was used as a less expensive alternative to make a deeper study of the flow field. Velocity fields and intake valves discharge coefficient were compared and analyzed, resulting in a good correlation in relation to the optical experiment.

This study involves the comparison of atomization characteristics of gasoline and ethanol produced by a single-hole gasoline direct injection (GDI) injector. Experiments were performed for the fuel spray characterization, such as: measuring the injected fuel mass flow rate, the droplet velocity and the droplet diameter of atomized fuel as a function of injection pressure. In the injected fuel mass flow rate measurements, an experimental apparatus was used consisting of a nitrogen cylinder, a source of generating pulses, a fuel tank as a pressure vessel and a precision weighing scale. To measure the fuel droplet velocity and droplet diameter, were used the known optical techniques: Laser Doppler Anemometry and Phase Doppler Anemometry (LDA/PDA), respectively. Thus, the performance of fuels can be compared. The average droplet velocity, droplet diameter and characteristic diameter, Sauter Mean Diameter (SMD), were evaluated and analyzed due to the injection pressure.

The purpose of this work is to present an experimental methodology to characterize the in-cylinder tumbling flow generated by a motored four-valve spark ignition single cylinder optical research engine. High-speed two-dimensional particle image velocimetry measurements were made in the symmetry vertical plane between the inlet and outlet valves. The velocity flow fields were recorded during the intake and compression strokes for three different engine speeds (1000, 1500 and 2000 rpm) at several crank angles. Vorticity, tumble ratio and kinetic energy were calculated and compared. Also, an evolution analysis of the main vortex center was made. As result, the tumble ratio and kinetic energy showed a decrease at the end of intake stroke. Flow field cyclic variation could be noticed. The methodology contributes to a better understanding of flow motion behavior, and consequently, the mixture formation process in spark ignition engines.

Gasoline direct injection (GDI) engines have very attractive potential for improving fuel economy and exhaust emissions, especially disadvantages of increased fuel consumption at part load. In this research, a study has been made on the investigations of stratified lean combustion in a wall-air guided type spark-ignition single cylinder optical research engine. Experiments were conducted at constant load (NIMEP 3 bar) using ethanol as fuel, for a wide range of injection, ignition and mixture formation parameters. Engine efficiency and combustion stability were evaluated at each excess air ratio. Optical visualization illustrated the spray behavior and flame propagation. Specific fuel consumption improvement was achieved with lean burn mixtures. Thus, combustion analysis data based on in-cylinder pressure measurement provide useful data for ethanol GDI engine development.

The design and development of highly efficient internal combustion engines require a thorough investigation of the fluid dynamic processes. This paper presents the experimentally determination and computational fluid dynamics simulations of the intake valves discharge coefficients of a four valve spark-ignition single cylinder research engine. The mass flow rate and air pressure were measured directly in the intake port for six different values of valve lift (4.68; 6.16; 7.48; 8.62; 9.46; and 10.49mm). The theoretical mass flow rates were obtained based on considerations of subsonic flow. Simulations were carried using the Star CCM+ commercial code. Mesh independence studies, using the velocity fields as monitors, have been made for reliability of the simulations. As a result, a methodology was successfully implemented to obtain the discharge coefficients experimentally and the simulations were validated with a maximum deviation of 6.62%.