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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.

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.

In this work, atomization parameters were analyzed by the image visualization of spray from a multi-hole direct injection injector, operating in a backpressure chamber. Such characteristics like cone angle and penetration were analyzed for similar fluids concerning gasoline and ethanol - EXXSOL D40 and EXXSOL D60 respectively under an environment pressure of 5 bar, to simulate incylinder condition, and injection pressure of 70, 90, 100 and 110 bar. To control the injection a Motec-M84 and a driver peak and hold were used. A high speed camera was used for recording images of injection process. The spray images were obtained by a 6504 frames per second recording process, applying shadowgraph technique and MatLab codes were written for image treatment. With the data generated, a comparison between the fluid parameters could be made for direct injection under pressurized environment.

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.

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%.

It can be said that the greatest engineering challenge of mobility it is not related to the energy shortage, but to its generation and sustainable use. In this context, the growing use of biofuels by high performance internal combustion engines represents a sustainable alternative from the economic, technological, social and environmental point of view. In some regions of the planet, the modern electric and hybrid vehicles may not be the most sustainable choice, since they face many obstacles regarding clean energy generation, reduced recharging station network, limited autonomy, expensive vehicle prices, and battery recycling. In Brazil since its launching in 2003, the fleet of Flex-Fuel vehicles moved by either ethanol or gasoline is ever increasing. It is worth mentioning that the biofuel has physical and chemical properties that could make its use more efficient than it is nowadays.

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.

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).

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.

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.