Search Results

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 work presents the development of an automotive turbocharger test stand where a hot gas generator is used to drive the turbocharger. The burner consists in a tubular combustion chamber, projected to operate burning gaseous fuels. The development of the test stand became necessary within the must to know turbochargers operational characteristics, since those information's are not always supplied by their manufacturers. By using a combustion chamber it's possible to simulate the real operational condition of the set. The test consists in recording the characteristic curves of the turbochargers, known as flow maps or performance maps. The necessary instrumentation is based on virtual instrumentation, where acquisition and control of the sensors are made by computer. In the development of the test stand, a MP-357 Master Power turbocharger, used in commercial heavy trucks, is used.

The new trends of the automotive market require the development of a new concept of engines using different types of fuel, mainly those resulting from alternative sources of energy. For this purpose those multi-fuel engines must function with higher energy efficiency therefore allowing for lower fuel consumption and a drastic reduction of exhaust emission. The multi-fuel engines available in the market display only one volumetric compression ratio, which leaves ample room for the development of a better level of fuel energy use. To achieve so, such an engine must count on a variable volumetric compression ratio, which, despite being technically possible, is not economically viable for a low cost product. The present project intends to create a system capable of achieving the best performance for all types of fuel through the variation of the boost pressure, viable for a low cost product, without changing its volumetric compression ratio.

This work presents the performance analysis of a radial turbine operating with different housing sizing. The objective is to determine the changes in turbine operational behavior by using different housing sizing. The parameter that characterizes the radial turbine housing is called A/R. This parameter associates the cross-sectional area with area radius from turbine centerline. The turbine tests are made in a hot gas test stand in which a tubular combustion chamber is used to drive the turbine. The turbine tested belongs to an automotive turbocharger, the Master Power APL-240. The turbine housings used are 0.48, 0.63 and 1.06 A/R. Through the experimental data recorded, it is also possible to obtain the turbine performance map. The results present the turbine performance map and a comparison between the pressure ratio and turbine power for each turbines housing used. The results show that by reducing the turbine A/R, the mass flow rate for a given expansion ratio also reduces.

This work presents the dynamic modeling of an automotive turbocharger in a hot gas test stand. The objective is to develop a methodology to determine the main turbocharger dynamic properties as moment of inertia, response time, static gain constant, frequency gain amplitude and phase shift. The turbocharger used is the Master Power APL-240 set. The moment of inertia is obtained through the deceleration curve from an instantaneous fuel cut-off in the combustion chamber. The response time and static gain constant, as well the frequency gain amplitude and phase shift curves in function of a signal frequency, are obtained through a step variation. The turbocharger is modeled as a first order system. It is also presented a turbocharger sine excitation by the combustion chamber, generating a rotational speed sine signal output that simulates an engine intermittent acceleration. The rotational speed signal frequency gain and phase shift are compared to the values obtained in the step curves.

In Brazilian market, Flex-Fuel vehicles represented over 90% of new light-duty vehicles sold in 2009. These vehicles can use gasoline blended with anhydrous ethanol (20 to 25% v/v), 100% of hydrous ethanol (contains from 6,2 to 7,4% w/w of water) or any blend of these fuels. An experimental investigation was done to study fuel consumption, emissions and in-cylinder pressure data of a Flex-Fuel Otto engine, 1.4 L, 4 cylinders. It used gasoline with 22% of anhydrous ethanol as a reference fuel (E22). E22 was blended with different hydrous ethanol contents such as 50% (H50) and 80% (H80), also a 100% hydrous ethanol H100) was used. The main fuel properties were analyzed as part of this work. To control the engine operation, a programmable ECU (Engine Control Unit) was used, allowing spark timing calibration either for maximum break torque (MBT) or to keep the engine below the knocking limit.

This work treats of a project aiming the construction of a virtual panel of instruments of a general aviation aircraft. In addition, it could be applied the other vehicles as automobiles, trucks and ships. This work follows the tendency of recent researches of NASA for interfaces between pilot and aircraft that will permit to the general aviation community access to modern multifunctional displays that will become the piloting easier and safer. This work consists in developing software for acquisition and visualization and in specification of an analogical/digital conversion card and low cost sensors that will be used to measure the variables related to the movement of the aircraft.

This work reports a conception phase of a piston engine global model. The model objective is forecast the motor performance (power, torque and specific consumption as a function of rotation and environmental conditions). Global model or Zero-dimensional is based on flux balance through each engine component. The resulting differential equations represents a compressive unsteady flow, in which, all dimensional variables are areas or volumes. A review is presented first. The ordinary differential equation system is presented and a Runge-Kutta method is proposed to solve it numerically. The model includes the momentum conservation equation to link the gas dynamics with the engine moving parts rigid body mechanics. As an oriented to objects model the documentation follows the UML standard. A discussion about the class diagrams is presented, relating the classes with physical model related. The OOP approach allows evolution from simple models to most complex ones without total code rewrite.

This work compares procedures specified on standard ISO-1585 applicable to piston engine bench dynamometer, with two quasi-static procedures. The first one is based on maintain constant the engine rotation and the load during 1 minute and then modified the work conditions. This procedure results in a step test when using a continuous data acquisition system. The other one is based on change the engine rotation and load continuously during the test, in a way that load and rotation stay ever on PID equilibrium. This allow, during one season, acquire hundred of engine operating condition points. The objective is to demonstrate that these tests procedures accomplish the Brazilian standard and they don't introduce news mistakes. The advantage of these procedures is to reduce the time required to execute engine test. Other advantage is allowing the process automation. Power curves are shown for a four cylinders in line, 1300 cm3, 16 valves engine measured following the three procedures.

This work presents the experimental determination of an automotive turbocharger flow map, by using a flux test stand. This equipment is able to reproduce and measure the main characteristics of an intake and exhaust flows of an automotive engine. To build the compressor and turbine flow maps, the experimental data should be treated through an empirical model. Flow maps of two turbochargers are presented. The first flow map presented was used to validate the data treating method. The validation process made use of published GT12 Garrett turbocharger data. The data treating method was applied on the experimental dada of T2 Garrett turbocharger obtained on the flux test stand. The flow maps build are shown, and operational limits are identified on then. These flow maps give essential information to choose the most suitable turbocharger for a specific internal combustion engine.

A multi-hole direct injection injector was studied by means of image analysis. Methodologies based on an automatic process of cone angle measurement and edge detection were applied for the spray images generated by a 100 bar injection pressure discharged into a pressurized rigid chamber. A criterion based on pixel values was taken to localize the spray edges as angular coordinates and also with 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. Using the written MATLAB codes, a comparison of the effect of atmospheric back pressure, inside the chamber, on the spray pattern, cone angle and spray penetration were evaluated. The chamber was pressurized with 2.5, 5.0, 7.5 and 10 bar of back pressure. The tested fluid injected was EXXSOL D60 for simulating ethanol fuel behavior.

Gasoline is a complex mixture, composed of hundreds of different hydrocarbons. Surrogate fuels decrease the complexity of gasoline and are being used to improve the understanding of internal combustion engines (ICEs) fundamental processes. Computational tools are largely used in ICE development and performance optimization using simple fuels, because it is still not possible to completely model a commercial gasoline. The kinetics and interactions among all the chemical constituents are not yet fully understood, and the computational cost is also prohibitive. There is a need to find suitable surrogate fuels, which can reproduce commercial fuels performance and emissions behavior, in order to develop improved models for fuel combustion in practical devices, such as homogeneous charge compression ignition (HCCI) and spark ignition (SI) engines. Representative surrogate fuels can also be used in fuel development processes.

Exhaust Gas Recirculation - EGR - is a well-known technique to reduce NOx and it’s been applied on Diesel engines for a long time. Later studies and application found that other benefits can be achieved with PFI and GDI gasoline engines, such as pumping loss minimization and efficient knock control. Variable valve actuation valve-trains brought broader application possibilities as it enables full internal EGR control without external paths, high precision and response, as required on transient work modes. Comprehensive investigation on PFI and GDI Spark Ignition engines with external Hot EGR and Cooled EGR are widely available. However, variable valve actuation EGR control review on a flexfuel application is not well explored, and this paper is aimed at doing such.

This study involves the operation of the Common Rail Diesel Injection, atomization characteristics of fuel and reconditioning of diesel engine nozzles. The nozzles of the Common Rail system were repaired in order to give them optimum conditions of operation. For it be confirmed, the volume of Diesel injected was measured as a function of injection pressure, injection angle and the cone angle of the atomized fuel into new nozzles (control), used and reconditioned. In the evaluation of the volume, it was used a circuit consisting of a high pressure pump, a source of pulses and a reservoir of fuel oil. For the geometric characteristics of the fuel spray was used a high speed filming, 4000 frames per second, applying shadowgraphy techniques for measuring these angles. The experimental results allowed evaluating the types of changes in the nozzle after the reconditioning process.

Fossil fuels and biofuels usage in internal combustion engines are the main source for vehicular propulsion. This justifies the intense worldwide research and development to comply with the challenges of increasing efficiency and emissions reduction. The modeling of commercial fuels and engine combustion processes presents great challenges. There is also the need to better understand how different fuel components interact and influence engine combustion and performance parameters. In previous works, components selection and engine dynamometer tests were done to identify representative surrogate fuels for commercial Brazilian gasoline. It was concluded that formulations with n-heptane, iso-octane, toluene and ethanol can be used to model oxygenated gasolines. Methodologies were implemented to evaluate the influence of the fuel components on fuel properties and several engine combustion and performance parameters.

This study analyzes the design of a two-stage reusable satellite launch vehicle. This launcher was designed to orbit payloads of up to 500 kg to low orbits (LEO). Two RISCRAM™ jet engines (Rocket Ignited Supersonic Combustion Ramjet) power the first stage that is fully reusable. They aspirate atmospheric air and allows speeds of up to Mach 6, below 30 km, and Mach 15 above 40 km of altitude. The second stage is powered by a solid rocket motor that carries the payload at the orbital speed of Mach 24. In this work are presented details of the concept of the vehicle and an economic feasibility analysis of system operation. Launch cost estimative are made and compared to the values of the current satellite launchers that are not reusable. The conclusion of the article is that the proposed system would be able to reduce by an order of magnitude the cost of placing the kilogram of payload in low orbit.

This paper relates to the wind tunnel balance design that aims to meet the need for reliable but more affordable equipment that could accurately perform Aerodynamic measurements and act on three axes, being a Multitasking device, adaptable for prototypes of aircrafts, automobiles, buildings, sports products design, etc., through digital control that will measure the drag, lift and the aerodynamic pitch moment. The main task is stimulating creativity, to solve real problems and reduce technology dependence. The composite tubes used in the fixation of the "Sting-Compound" were chosen to avoid inaccurate measurements and have high flexural strength, even with a small cross section. That's feature is justified because the terminal velocity of wind tunnel is 50 m/s (97 knots), enabling to search many different model sizes and subsonic Reynolds speed regime.

The problems of vibration and noise from an internal combustion engine are common because of the wide variety of parts and components that make up an internal combustion engine. In recent years engines have evolved considerably in relation to the control of vibration and noise emitted, since these effects reduce the useful life of the internal components of the engine itself and, besides giving discomfort to the occupants of the vehicle. The objective of this work was to identify and describe the main sources of vibration and noise in an internal combustion engine. The methodology used in this work involved instrumentation of an internal combustion engine (Otto cycle), the experimental tests of the engine on a test bench and involved the application of analytical techniques for treatment and analysis of experimental data.

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.

Ethanol and gasoline are widely used with fuels in Otto cycle engines. These fuels have different heating power and octane number and the engine behaves differently depending on the type of fuel used. The objective of this study is to measure, compare and investigate the factors that affect the block vibration of an internal combustion engine as a function of the fuel used ethanol or gasoline. The experiment consisted of instrumenting the side of the engine block with an accelerometer to measure the level of vibration intensity of the engine running on a bench dynamometer varying engine speed and load conditions. The results showed that the engine vibration level increases with the increase in engine speed and load. The highest level of vibration was achieved in the region of maximum torque and maximum pressure combustion. The combustion process is mainly responsible for the highest level of vibration achieved with ethanol.