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Unburned hydrocarbon (UHC) and carbon monoxide (CO) emission sources are examined in an optical, light-duty diesel engine operating under low load and engine speed, while employing a highly dilute, partially premixed low-temperature combustion (LTC) strategy. The impact of engine load and charge dilution on the UHC and CO sources is also evaluated. The progression of in-cylinder mixing and combustion processes is studied using ultraviolet planar laser-induced fluorescence (UV PLIF) to measure the spatial distributions of liquid- and vapor-phase hydrocarbon. A separate, deep-UV LIF technique is used to examine the clearance volume spatial distribution and composition of late-cycle UHC and CO. Homogeneous reactor simulations, utilizing detailed chemical kinetics and constrained by the measured cylinder pressure, are used to examine the impact of charge dilution and initial stoichiometry on oxidation behavior.

Power supply systems play a very important role in applications of everyday life. Mainly, for low power generation, there are two ways of producing energy: electrochemical batteries and small engines. In the last few years many improvements have been carried out in order to obtain lighter batteries with longer duration but unfortunately the energy density of 1 MJ/kg seems to be an asymptotic value. If the energy source is an organic fuel with an energy density of around 29 MJ/kg and a minimum overall efficiency of only 3.5%, this device can surpass the batteries. Nowadays the most efficient combustion process is HCCI combustion which is able to combine high energy conversion efficiency and low emission levels with a very low fuel consumption. In this paper, an investigation has been carried out concerning the effects of the compression ratio on the performance and emissions of a mini, Vd = 4.11 [cm3], HCCI engine fueled with diethyl ether.

An experimental study of a glow plug engine combustion process has been performed by applying chemiluminescence imaging. The major intent was to understand what kind of combustion is present in a glow plug engine and how the combustion process behaves in a small volume and at high engine speed. To achieve this, images of natural emitted light were taken and filters were applied for isolating the formaldehyde and hydroxyl species. Images were taken in a model airplane engine, 4.11 cm3, modified for optical access. The pictures were acquired using a high speed camera capable of taking one photo every second or fourth crank angle degree, and consequently visualizing the progress of the combustion process. The images were taken with the same operating condition at two different engine speeds: 9600 and 13400 rpm. A mixture of 65% methanol, 20% nitromethane and 15% lubricant was used as fuel.

Power supply systems play a very important role in everyday life applications. There are mainly two ways of producing energy for low power generation: electrochemical batteries and small engines. In the last few years, many improvements have been carried out in order to obtain lighter batteries with longer durations but unfortunately the energy density of 1 MJ/kg seems to be an asymptotic value. An energy source constituted of an organic fuel with an energy density around 29 MJ/kg and a minimum overall efficiency of only 3.5% could surpass batteries. Nowadays, the most efficient combustion process is HCCI combustion which has the ability to combine a high energy conversion efficiency with low emission levels and a very low fuel consumption. The present paper describes an investigation carried out on a modified model airplane engine, on how a pure HCCI combustion behaves in a small volume, Vd = 4.11 cm3, at very high engine speeds (up to 17,500 [rpm]).

Nowadays the power supplying systems have a fundamental importance for all small and portable devices. For low power applications, there are two main ways for producing power: electrochemical batteries and mini engines. Even though in recent years many developments have been carried out in improving the design of batteries, the energy density of 1MJ/kg seems to be an asymptotic value. If the energy source is a hydrocarbon fuel, whose energy density is 46 MJ/kg, with an overall efficiency of only 2.5 % it is possible to surpass the electrochemical batteries. On the other hand, having a mini engine, as energy source, implies three main problems: vibrations, noise and emissions. A light (230 g) model airplane engine with a displacement volume of 4.11 cm3 and a geometrical compression ratio of 13.91 has been studied. The work carried out in this paper can be divided basically in three parts.

High-speed video imaging in a swirl-supported (Rs = 1.7), direct-injection heavy-duty diesel engine operated with moderate-to-high EGR rates reveals a distinct correlation between the spatial distribution of luminous soot and mean flow vorticity in the horizontal plane. The temporal behavior of the experimental images, as well as the results of multi-dimensional numerical simulations, show that this soot-vorticity correlation is caused by the presence of a greater amount of soot on the windward side of the jet. The simulations indicate that while flow swirl can influence pre-ignition mixing processes as well as post-combustion soot oxidation processes, interactions between the swirl and the heat release can also influence mixing processes. Without swirl, combustion-generated gas flows influence mixing on both sides of the jet equally. In the presence of swirl, the heat release occurs on the leeward side of the fuel sprays.

Electronic systems in vehicles characteristically consist of several distributed electronic control units (ECUs) from different suppliers. This situation hinders the integration of automotive systems and increases the overall costs due to individual solutions coming from each supplier. In order to get rid of these disadvantages, the French-German project OSEK/VDX was founded and is now drawing attention worldwide. OSEK/VDX worked out a respective specification to standardize services and protocols of communication, network management and a real-time operating system. An overview of the current state of OSEK/VDX including specifications and harmonization process with ISO is given. Furthermore a description of the Modistarc project working on methodologies and tools for conformance testing of commercial OSEK/VDX implementations is contained.

Nowadays for small-scale power generation there are electrochemical batteries and mini engines. Many efforts have been done for improving the power density of the batteries but unfortunately the value of 1 MJ/kg seems to be asymptotic. If the energy source is an organic fuel which has an energy density of around 29 MJ/kg with a minimum overall efficiency of only 3.5%, this device would surpass the batteries. This paper is the fifth of a series of publications aimed to study the HCCI combustion process in the milli domain at high engine speed in order to design and develop VIMPA, Vibrating Microengine for Low Power Generation and Microsystems Actuation. Previous studies ranged from general characterization of the HCCI combustion process by using metal and optical engines, to more specific topics for instance the influence of the boundary layer and quenching distance on the quality of the combustion.

In-cylinder flow measurements, conventional swirl measurements and CFD-simulations have been performed and then compared. The engine studied is a single cylinder version of a Scania D12 that represents a modern heavy-duty truck size engine. Bowditch type optical access and flat piston is used. The cylinder head was also measured in a steady-flow impulse torque swirl meter. From the two-dimensional flow-field, which was measured in the interval from -200° ATDC to 65° ATDC at two different positions from the cylinder head, calculations of the vorticity, turbulence and swirl were made. A maximum in swirl occurs at about 50° before TDC while the maximum vorticity and turbulence occurs somewhat later during the compression stroke. The swirl centre is also seen moving around and it does not coincide with the geometrical centre of the cylinder. The simulated flow-field shows similar behaviour as that seen in the measurements.

Laser-Rayleigh imaging has been employed to measure the relative fuel concentration in the gaseous jet region of DME sprays. The measurements were performed in an optically accessible diesel truck engine equipped with a common rail injection system. A one-hole nozzle was used to guarantee that the recorded pressure history was associated with the heat release in the imaged spray. To compensate for the low compression ratio in the modified engine the inlet air was preheated. Spray development was studied for two levels of preheating, from the start of injection to the point where all fuel was consumed. The results indicate that there is a strong correlation between the amount of unburned fuel present in the cylinder and the rate of heat release at a given time. The combustion can not be described as purely premixed or purely mixing-controlled at any time, but always has an element of both. After all fuel appears to have vanished there is still an extended period of heat release.

An experimental and computational study of the near-wall combustion in a Homogeneous Charge Compression Ignition (HCCI) engine has been conducted by applying laser based diagnostic techniques in combination with numerical modeling. Our major intent was to characterize the combustion in the velocity- and thermal boundary layers. The progress of the combustion was studied by using fuel tracer LIF, the result of which was compared with LDA measurements of the velocity boundary layer along with numerical simulations of the reacting boundary layer. Time resolved images of the PLIF signal were taken and ensemble averaged images were calculated. In the fuel tracer LIF experiments, acetone was seeded into the fuel as a tracer. It is clear from the experiments that a proper set of backgrounds and laser profiles are necessary to resolve the near-wall concentration profiles, even at a qualitative level.

For the development of future safety-relevant automotive electronic systems a thorough adaptation of the existing design process is necessary to consider safety and reliability in a more systematic way. In this paper an approach for a new design methodology is presented. It is based on the V-Model which is the established process model for the development of electronic and software systems in the automotive domain. For an advanced consideration of safety and reliability the existing process is extended by a second V (with process elements that have a special focus on safety and reliability) to a “Double V”. The new elements are interconnected with the existing ones at several points of time during the development process. By a defined information exchange between the two Vs continuity in the methodology is guaranteed. Basis for the extension are experiences of the aerospace domain that were adopted to automotive conditions.

During development of an air assisted, direct injection combustion system, it was found that an air pulse during the late part of compression stroke significantly shortened the combustion duration and extended the lean limits of the engine. The effect of an injection of pure air through an air assist direct injector was studied with Particle Image Velocimetry, PIV. Results showed that an air pulse during the compression stroke significantly speeded up in-cylinder velocities, which also was showed in the heat release analysis. A system to use low density seeding particles was developed and is presented in the paper.

A newly developed cross flow cylinder head has been used for comparison between throttled and unthrottled operation using late intake valve closing. Pressure measurements have been used for calculations of indicated load and heat-release. Emission measurements has also been made. A model was used for estimating the amount of residual gases resulting from the different load strategies. Unthrottled operation using late intake valve closing resulted in lower pumping losses, but also in increased amounts of residual gases, using this cylinder head. This is due to the special design, with one intake valve and one exhaust valve per camshaft. Late intake valve closing was achieved by phasing one of the camshafts, resulting in late exhaust valve closing as well. With very late phasing - i.e. low load - the effective compression ratio was reduced. This, in combination with high amount of residual gases, resulted in a very unstable combustion.

The California LEV1 II program will be introduced in the year 2003 and requires a further reduction of the exhaust emissions of passenger cars. The cold start emissions represent the main part of the total emissions of the FTP2-Cycle. Cold start emissions can be efficiently reduced by injecting secondary air (SA) in the exhaust port making compliance with the most stringent standards possible. The thermochemical conditions (mixing rate and temperature of secondary air and exhaust gas, exhaust gas composition, etc) prevailing in the exhaust system are described in this paper. This provides knowledge of the conditions for auto ignition of the mixture within the exhaust manifold. The thus established exothermal reaction (exhaust gas post-combustion) results in a shorter time to light-off temperature of the catalyst. The mechanisms of this combustion are studied at different engine idle conditions.

This article gives an overview of the CARTRONIC® based safety analysis (CSA) including an approach for the automatic determination of failure dependencies in automotive systems. CSA is a safety analysis in an early stage of product development. The goals are to identify safety critical components as soon as practicable in the product development process and to automate the analysis as far as possible. This implies that the system view is abstract, i.e. independent of a certain realization just regarding system functionality. In the CSA so called global failure effects will be systematically identified and assessed regarding severity of potential injuries. Global failure effects are especially important because they reveal failures within the system to the outside world (see also definition 3.1). Additionally the CSA keeps track of failure dependencies and supports the integration of safety measures in the system structure.

A specially designed cylinder head, enabling unthrottled operation with a standard cam-phasing mechanism, was tested in an optical single-cylinder engine. The in-cylinder flow was measured with particle image velocimetry (PIV) and the results were compared with heat release and emission measurements. The article also discusses effects of residual gas and effective compression ratio on heat-release and emissions. The special design of the cylinder head, with one inlet and one exhaust valve per camshaft, made it possible to operate the engine unthrottled at part load. Cam phasing led to late inlet valve closing, but also to increased valve overlap. The exhaust valve closing was late in the intake stroke, resulting in high amounts of residual gases. Two different camshafts were used with late inlet valve closing. One of the camshafts had shorter valve open duration on the phased exhaust cam lobe.

Ion current measurements can give information useful for controlling the combustion stability in a multi-cylinder engine. Operation near the dilution limit (air or EGR) can be achieved and it can be optimized individually for the cylinders, resulting in a system with better engine stability for highly diluted mixtures. This method will also compensate for engine wear, e.g. changes in volumetric efficiency and fuel injector characteristics. Especially in a port injected engine, changes in fuel injector characteristics can lead to increased emissions and deteriorated engine performance when operating with a closed-loop lambda control system. One problem using the ion-current signal to control engine stability near the lean limit is the weak signal resulting in low signal to noise ratio. Measurements presented in this paper were made on a turbocharged 9.6 liter six cylinder natural gas engine with port injection.

In this paper a fast NOx model is presented which can be used for engine optimization, aftertreatment control or virtual mapping. A cylinder pressure trace is required as input data. High calculation speed is obtained by using table interpolation to calculate equilibrium temperatures and species concentrations. Test data from a single-cylinder engine and from a complete six-cylinder engine have been used for calibration and validation of the model. The model produces results of good agreement with emission measurements using approximately 50 combustion product zones and a calculation time of one second per engine cycle. Different compression ratios, EGR rates, injection timing, inlet pressures etc. were used in the validation tests.

High-speed laser diagnostics was utilized for single-cycle resolved studies of the formaldehyde distribution in the combustion chamber of an HCCI engine. A multi-YAG laser system consisting of four individual Q-switched, flash lamp-pumped Nd:YAG lasers has previously been developed in order to obtain laser pulses at 355 nm suitable for performing LIF measurements of the formaldehyde molecule. Bursts of up to eight pulses with very short time separation can be produced, allowing capturing of LIF image series with high temporal resolution. The system was used together with a high-speed framing camera employing eight intensified CCD modules, with a frame-rate matching the laser pulse repetition rate. The diagnostic system was used to study the combustion in a truck-size HCCI engine, running at 1200 rpm using n-heptane as fuel. By using laser pulses with time separations as short as 70 μs, cycle-resolved image sequences of the formaldehyde distribution were obtained.