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The internal combustion engines require an efficient cooling system, the high temperatures generates at the time of combustion, reaching 2500 K peak burned gas. The materials used in the construction of the cylinder must operate within a maximum value, as well as the fluid film of lubricant oil. A bad dimensioned cooling system can lead to serious consequences such as loss of engine performance and/or efficiency, pre-ignition and increased exhaust emissions and may even lead to the destruction of the engine. In the torch ignition system overheating of the pre-chamber is even more critical and may lead to significant losses. Thus the torch ignition system requires an efficient cooling to prevent deterioration of the pre-chamber and consequently the engine caused by overheating. The solution proposed to resolve this inconvenience is the use of the cooling gallery in the cylinder head, for cooling the pre-chamber that is selected.

An torch ignition system with homogeneous charge is numerically analyzed using a one-dimensional computational model. The new ignition system is implemented in a four-cylinder engine, spark ignition, 1600 cm3, 16 valves. Parameters such as mass burn fraction profile and pressure vs crank angle are compared with experimental data obtained with the torch ignition system operating homogeneous charge with stoichiometric mixture. The computational model uses information such as the pre-chamber pressure as a function of crack angle, intake and exhaust pressure, volumetric efficiency, maps of injection and ignition, valve discharge and valve intake coefficient, lifting valve, laminar flame speed, among others parameters.

Stringent automotive emissions and fuel economy regulations have been bringing challenges for the development of new engine technologies to achieve greater levels of efficiency and pollutants reduction. In this scenario the homogeneous charge pre-chamber jet ignition system (HCJI) enables lean operation due the jet combustion gases emerging from the small pre-chamber combustor as the ignition source for main chamber combustion in an internal combustion engine. The present computational work was carrying out to investigate the interaction between the pre-chamber and main chamber fluid dynamics events. This CFD research was performed and validated with a experimental data for a single cylinder of a 4-stroke indirect fuel injection engine under the motoring condition running at 4500 rpm with 50% wide open throttle condition.

The aim of this work is to present the preliminary performance studies of the unmanned, lightweight (less than 10 kg), supersonic research aircraft. The studies comprise the typical mission for the aircraft's first supersonic version, based on the aerodynamic, thrust, and mass characteristics presented in a previous work. The aircraft, named as “Pohox”, is an Unmanned Air Vehicle, or “UAV”, and is intended to be the flying test bed for a multi cycle engine capable to provide thrust in subsonic, transonic and supersonic regimes. Different tools have been developed to perform the analysis. In the analysis, different flight paths are considered in order to provide insights in terms of fuel consumption, altitude and speed gain. Aircraft ‘excess power’ diagrams have been generated, to provide guidance for the definition of the flight paths to be analyzed. Drag dependency with Mach number is considered in the analysis.

A burning process in a combustion chamber of an internal combustion engine is very important to know the maximum temperature of the gases, the speed of combustion, and the ignition delay time of fuel and air mixture exact moment at which ignition will occur. The automobilist industry has invested considerable amounts of resources in numerical modeling and simulations in order to obtain relevant information about the processes in the combustion chamber and then extract the maximum engine performance control the emission of pollutants and formulate new fuels. This study aimed to general construction and instrumentation of a shock tube for measuring shock wave. As specific objective was determined reaction rate and ignition delay time of ethanol doped with different levels of additive enhancer cetane number. The results are compared with the delays measured for the ignition diesel and biodiesel.

It developed a design and construction methodology of a stratified charge torch ignition system for an Otto engine aiming fuel consumption and pollutant emission reduction. The torch ignition system is made of a combustion pre-chamber equipped with a direct fuel injector, an air injector and a spark plug. Fuel is directly injected in the pre-chamber aiming the formation of a lightly rich air fuel mixture. The combustion process starts in the pre-chamber and as the pressure rises, combustion jet flames are produced through interconnection nozzles into the main chamber. The high thermal energy of the jet flames reduces the combustion time, increases the combustion efficiency and allows the engine to efficiently burn lean air fuel mixture of several kinds of fuel in the main chamber, even those that are difficult to ignite. After the combustion takes place in the pre-chamber, air is also injected to help the exhaust process of the combustion products of the previous cycle.

This work shows procedures for analyzing sprays produced by a direct injection injector. The parameters studied were tip penetration, spray pattern, cone angles and velocity profiles. Two different experimental procedures were applied. The first one to get knowledge of the initial stage of injection consisted in recording images in 4000 Hz. With the data obtained, the penetrations and penetration rates were evaluated. The second experimental procedure consisted of using the Particle Image Velocimetry technique to get images and velocity data for getting knowledge of spray pattern, external and internal cone angle and velocity profiles of the spray fully developed. Gasoline and ethanol were the two fluids tested on the experiments. The results showed larger cone angles for gasoline, linear decreasing behavior for velocities on the linear velocity profiles and a transient stage for the magnitude of the velocities in the initial stage of injection.

For metallic tanks in contact with aqueous solution, it is always observed the presence of electrochemical corrosion. This process can cause both economic and environmental damage. In the automotive industry, fuel tanks systems have been studied in order to propose new materials to replace the plastic tanks or tanks with metallic coatings. Plastic tanks have the disadvantage of not being recyclable. In the other hand, for metallic coated tanks, tin is used as a coat material and, for this reason, the external tank side must be painted, making its productive process more expensive and generating higher amount of waste. Nowadays, organic-metallic coated tanks, in which, nickel and aluminum are the metals present, can be found. These coatings show potential application; because they do not use heavy metals in their composition and they do not require external painting, allowing a lower production cost.

The focus of this study was to create a methodology to evaluate spray characteristics in a gasoline direct injection injector by means of an automatic process. Computational codes were used to get information about cone angle and breakup length based on images got from injection process. A mathematical function was created to locate the boundaries of the spray and the cone angle was studied as the angle of arcs situated within these boundaries. The centre of the arc was located on the orifice of the injector and a value of angle was associated with several distances from orifice. The breakup length was associated as a distance from the orifice of an arc formed by a group of pixels with the maximum standard deviation related to the values of these pixels. The velocity field was studied by the Particle Image Velocimetry technique. Three fluids were tested at this work: water, ethanol and gasoline.

The technological development of automotive engines is focused on alternative energy sources and optimized use of conventional fuels. The current flexible engines in Brazil can operate with gasohol and ethanol blends in any proportion, but the flexibility is restricted to liquid fuels. The present investigation consists on the use of electronic injection systems for ethanol and for CNG, allowing the use of these fuels simultaneously. The objective of this work is to determine the best proportion of CNG-ethanol mixture in order to maximize the use of the natural gas, fuel which offers the lowest BSFC on conventional SI engines. The low volumetric efficiency inherent in the use of CNG is compensated by the injection of a small quantity of ethanol. The latent heat of vaporization of the alcohol is used to take heat from the intake air and increase its mass, taking advantage from the high latent heat of vaporization of the ethanol and the low BSFC of the CNG.

The torch ignition system consists in the inflammation of the air/fuel mixture by means of gases jet flames that constitute ignition lines. Engines with this feature have a cavity or combustion pre-chamber, physically separate from the main chamber. In these systems happens a larger turbulence generation, due the movement of the gases inside the pre-chamber and through the interconnection orifices. The charge stratification, by means of an auxiliary inlet fuel system, also contributes for the fast and insurance inflammation of lean mixtures and the most varied combustible, including the difficult direct spark ignition fuels. This work presents the design elaboration of combustion pre-chamber from an analysis of the influence of the main constructive parameters in the combustion process.

In this work is proposed the installation of a turbocharger in a low dislocated volume engine, aiming to achieve a higher effective mean pressure and air fuel mixture density, for a better performance of the converted engine. This analysis is made through experimental tests in a break bench, following the Brazilian standard NBR ISO 1585. The results presented shows the basic behavior of the torque curves, power and gas emission, which reflects the changes in performance with both fuels for a aspirated and turbocharged engine, for all the engine rotation speeds. These results show the technical and economical viability of the conversion to Vehicular Natural Gas of a low cc engine, when adapted a commercial turbocharger kit.

This work presents a full analysis of a bi-fuel engine converted to natural gas and aims to survey the main performance losses and the advantages in specific consumption and toxic emissions. With this purpose, dynamometric tests and curves survey of a Fiat Palio 1.6, 16V engine, according to Standard NBR ISO 1585. Tests were made using diverse mixers, trying to obtain the losses caused by this device when the engine is working with gasoline, after the conversion. Tests were performed for different ignition advances, with manual and electronic VNG flow control systems. Trials for many differents low gear engine regulation, looking for consumption reduction and lower emission rates. The gas pressure reducer was tested with and without heating, showing differents results, mainly for emission rates. Other than comparing different components and different engine operation conditions, an analysis of two different natural gas conversion kits were performed, both extensile used in Brazil.