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The work focuses on studying ethanol spray behavior injected directly inside a spark ignited internal combustion engine in the compression stroke. An experimental procedure for measuring spray penetration and spray overall cone angle produced by a multi-hole direct injector was developed by means of computational codes written in Matlab environment for working with images of spray injections and to acquire calculated results in an automatic way. The shadowgraph technique with back continuous illumination associated with a high speed recording image process was used in a single cylinder optical research engine for acquiring images of Brazilian ethanol fuel injected at 120° before the top dead center of compression stroke. The process of spray injections occurred with engine speeds of 1000 rpm, 2000 rpm and 3000 rpm. The results showed that spray penetrations decrease and spray cone angle increase when the engine speed is raised.

The Stratified Torch Ignition (STI) engine is capable of operating with lean mixture and low cyclic variability. These characteristic significantly decreases fuel consumption and emission levels. In the STI engine the combustion starts at a pre-combustion chamber where a stoichiometric mixture is ignited by an electrical spark. Pressure increase in the pre-combustion chamber push the combustion jet flames through a calibrated nozzle to be precisely targeted into the main chamber. These combustion jet flames endowed with high thermal and kinetic energy assures a fast and stable combustion of a lean mixture formed at the main chamber. A STI prototype were built and tested. The main combustion parameters were obtained from the in-cylinder pressure measured during the experiments. A combustion analysis is carried out to explain the significant improvement of the STI engine in regard to the baseline engine which was used as workhorse for the prototype engine construction.

The emission of nitric oxide (NOx) is the most difficult to limit among numerous harmful exhaust gas components. The NOX emission of internal combustion engines is mainly NO, but it will be oxidized into NO2 quickly after entering the air. NO is formed inside the combustion chamber in post-flame combustion by the oxidation of nitrogen from the air in conditions that are dependent on the chemical composition of the mixture, temperature and pressure. The correlation between NO emissions and temperature in the combustion chamber is a result of the endothermic nature of these reactions and can be described by extended Zeldovich Mechanism. The stratified torch ignition engine is able to run with lean mixture and low cyclic variability. Due to lean operation, the in-cylinder temperature of the STI engine is significantly lower than the conventional spark ignited one. This fact lead to a substantial reduction in NOx specific emission.

A global effort has been made by the scientific community to promote significant reduction in vehicle engine out-emission. To comply with this goal a stratified torch ignition (STI) engine is built from a commercial existing baseline engine. In this system, combustion starts in a pre-combustion chamber, where the pressure increase pushes the combustion jet flames through calibrated nozzles to be precisely targeted into the main chamber. These combustion jet flames are endowed with high thermal and kinetic energy, being able to generate a stable lean combustion process. The high kinetic and thermal energy of the combustion jet flame results from the load stratification. The engine out-emissions of CO, HC and CO2 of the STI engine are presented, analyzed and compared with the baseline engine. The STI engine showed a significant decrease in the specific emissions of CO and CO2.

The growing demand for more efficient and less polluting engines has lead the scientific community to further develop the road map engine technologies, including direct fuel injection. Direct injection research demands the investigation of spray formation and its characteristics. The present work performs the characterization of the macroscopic parameters of ethanol sprays (E100) produced with a fuel gauge pressure of 80 bar and gauge back pressures of 0, 5 and 10 bar. The sprays analysis was performed using high speed filming by means of Shadowgraph technique. Computational routines of matrix analysis were applied to measure the spray cone angles, penetration and penetration rate. The spray visualization demanded an experimental apparatus composed of a pressurized cylinder with nitrogen, a fuel tank as pressure vessel, an injection driver equipped with a peak and hold module controlled by a MoteC M84, a Phantom V7.3 high speed camera and LEDs for illumination.

In the present work it was studied the flow around the intake and discharge valves of the HONDA CBR 600RR Engine, used in Formula SAE by the team of CEFET-MG, Formula Cefast. Presenting the methodology and experimental results in the measurement of the reversal discharge coefficient of the intake port and the discharge coefficient of exhaust valve of the engine used in the prototype, serving as a starting point for further studies and development of the prototype drive system. These experimental tests were performed on the flow bench infrastructure of the Pontificia Universidade Católica de Minas Gerais, PUC-MG, using the engine head, same model as used in the Formula Cefast team prototype. Necessary parts and adaptations for tests were developed, such as a mechanism for opening and closing the valves during the experiment.

It has been largely announced that automotive industry is going through a disruption moment regarding applied powertrain technologies due to the efforts to decrease CO2 and pollutant gases emission, mainly through related legislations of different countries and regions. European and Asian future legislations are going to demand some electrification introduction, whether hybrid or fully electric, but even different technologies such as fuel cells and synthetic fuels over the next few years. In Brazil, with the upswing of biofuels use, considering a well to wheel CO2 emission calculation, the usage of hydrated ethanol or ethanol mixed up with gasoline in different proportions is a great solution for a continuous and progressive automotive fleet decarbonization, in parallel or associated with electrification, in a favorable pace for the market conditions.

A CFD three-dimensional analysis of an internal combustion engine was carried out to evaluate the gasoline-ethanol E27 fuel spray and flow characteristics using variable valve timing (VVT) technology. In this study, the fuel injection has been made using port fuel injection (PFI) and the simulations modeled two conditions of valve timing: baseline and retarding the intake valve opening (IVO) 40°. The dynamic performance of this numerical model was validated comparing simulation results of cylinder pressure, mass burned fraction, cylinder temperature, and heat release with experimental data. The effects of in-cylinder fluid flow patterns, such as tumble and swirl, on combustion were numerically investigated for the two studied conditions and it was verified an extreme reduction of swirl when IVO is retarded, besides differences in tumble and cross-tumble.

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.

Atomization parameters from the spray produced by a direct injection injector, operating into an engine with optical access were analyzed in this work. Parameters such as cone angle, penetration and spray geometry for determined crank angles and different rotations, with the respective variability, were evaluated for ethanol injection. Images from spray injection were captured for the specified rotation conditions for the angle and geometry analysis. For the penetration analysis, the image acquisition occurred with crank angle variation, obtaining a mean value with respect to the spray displacement of a point of maximum concentration on a specified direction. Lines were adjusted to the penetration data and the penetration rates (velocities) were evaluated through its slopes. For the cone angle and geometry study, an automatic routine in Matlab environment for image processing was used.

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%.

Direct inject engine provides increased possibilities to work with injection strategies in order to achieve better efficiency. Some ethanol properties such as the higher octane number, the latent heat of vaporization as well as the faster laminar speed made ethanol one of the most promising biofuels. These properties help to achieve knock suppression in a SI engine and therefore allow the use of higher volumetric compression ratio, which is one of the key factors in efficiency improvement. Several studies have showed ethanol as a way to reduce soot formation in direct injection engines as the oxygen molecule reduces the locally fuel-rich region. The use of ethanol contributes significantly to the reduction of total hydrocarbon (THC) and carbon monoxide (CO).

In the actual context, Researchers are making efforts for becoming mobility more sustainable. Whithin it context, the strategy of direct injection of renewable ethanol fuel in spark ignition engines is an interesting alternative for substitution of fossil fuels. In Brazil, the majory part of ethanol fuel production is provenient of sugar cane that has the potential to absorb great quantity of carbon dioxide through the photosynthesis process. The focus of this study was to create a very low computational cost methodology for evaluating the shape of sprays produced by an inwardly opening pressure-swirl injector. The referred injector is to be used in four stroke spark ignition engines for delivering fuel directly inside the combustion chamber. The spray geometry was then predicted by numerical calculations of single droplets trajectories in a purely lagrangian approach. The working fluid injected considered was EXXSOL D60.