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Vehicle surface contamination is an important design consideration as it affects drivers’ vision and the performance of onboard camera and sensor systems. Previous work has shown that eddy-resolving methods are able to accurately capture the flow field and particle transport, leading to good agreement for vehicle soiling with experiments. What is less clear is whether the secondary breakup, coalescence, and evaporation of liquid particles play an important role in spray dynamics. The work reported here attempts to answer this and also give an idea of the computational cost associated with these extra physics models. A quarter-scale generic Sports Utility Vehicle (SUV) model is used as a test case in which the continuous phase is solved using the Spalart-Allmaras Improved Delayed Detached Eddy Simulation (IDDES) model. The dispersed phase is computed concurrently with the continuous phase using the Lagrangian approach.

Long-term reliability is one of the major requirements for the operation of automotive exhaust aftertreatment systems based on selective catalytic reduction (SCR). For an efficient reduction of nitrogen oxides in the SCR catalyst it is desirable that the thermolysis of the injected urea water solution (UWS) is completed within the mixing section of the exhaust system. Urea might undergo a number of secondary reactions leading to the formation of solid deposits on system walls. A deeper understanding of the mechanisms and influence factors is a basic requirement to prevent and predict undesired decomposition products. This paper outlines the mechanisms of UWS transport and deposition on a typical mixing element geometry. The conditions leading to deposit formation were investigated based on optical and temperature measurements in a box with optical access. A good correlation with the deposit location observed at the close-to-series exhaust system was found.

In Gasoline Direct Injection engines, direct exposure of the injector to the flame can cause combustion products to accumulate on the nozzle, which can result in increased particulate emissions. This research observes the impact of injector fouling on particulate emissions and the associated injector spray pattern and shows how both can be reversed by utilising fuel detergency. For this purpose multi-hole injectors were deliberately fouled in a four-cylinder test engine with two different base fuels. During a four hour injector fouling cycle particulate numbers (PN) increased by up to two orders of magnitude. The drift could be reversed by switching to a fuel blend that contained a detergent additive. In addition, it was possible to completely avoid any PN increase, when the detergent containing fuel was used from the beginning of the test. Microscopy showed that increased injector fouling coincided with increased particulate emissions.

Control of NOx and Particulate Matter (PM) emissions from diesel engines remains a significant challenge. One approach to reduce both emissions simultaneously without fuel economy penalty is the reformed exhaust gas recirculation (REGR) technique, where part of the fuel is catalytically reacted with hot engine exhaust gas to produce a hydrogen-rich combustible gas that is then fed to the engine. On the contrary to fuel cell technology where the reforming requirements are to produce a reformate with maximized H2 concentration and minimized (virtually zero) CO concentration, the key requirement of the application of the exhaust gas fuel reforming technique in engines is the efficient on-demand generation of a reformate with only a relatively low concentration of hydrogen (typically up to 20%).

The blending of oxygenated compounds with gasoline is projected to increase because oxygenate fuels can be produced renewably, and because their high octane rating allows them to be used in substitution of the aromatic fraction in gasoline. Blending oxygenates with gasoline changes the fuels' properties and can have a profound affect on the distillation curve, both of which are known to affect engine-out emissions. In this work, the effect of blending methanol and ethanol with gasoline on unburned hydrocarbon and particulate emissions is experimentally determined in a spray guided direct injection engine. Particulate number concentration and size distribution were measured using a Cambustion DMS500. These data are presented for different air fuel ratios, loads, ignition timings and injection timings. In addition, the ASTM D86 distillation curve was modeled using the binary activity coefficients method for the fuel blends used in the experiments.

The regeneration of a Diesel Particulate Filter (DPF) is dependent on both the amount and type of soot present on the filter. The objective of this work is to understand how the fuel can affect this ease with which soot can be oxidized. This soot was produced in a two-cylinder four-stroke direct-injection diesel engine, operated with a matrix of fuels with varying aromatic and sulphur level. Their oxidation behaviour in different environments was determined by Temperature Programmed Oxidation in TGA and a six-flow reactor. Transmission electron microscopy was used to examine the soot morphology. Oxidation with only O2 shows oxidation temperatures strongly dependent on the fuel type. Soot oxidation in the presence of NO and a Pt-catalyst results in a lower oxidation temperature. SO2 has an inhibiting effect leading to higher soot oxidation temperature.

Limits on the total future potential of biodiesel fuel due to the availability of raw materials mean that ambitious 20% fuel replacement targets will need to be met by the use of both first and next generation biodiesel fuels. The use of higher percentage biodiesel blends requires engine recalibration, as it affects engine performance, combustion patterns and emissions. Previous work has shown that the combustion of 50:50 blends of biodiesel fuels (first generation RME and next generation synthetic fuel) can give diesel fuel-like performance (i.e. in-cylinder pressure, fuel injection and heat release patterns). This means engine recalibration can be avoided, plus a reduction in all the regulated emissions. Using a 30% biodiesel blend (with different first and next generation proportions) mixed with Diesel may be a more realistic future fuel.

Synthetic fuels are expected to play an important role for future mobility, because they can be introduced seamlessly alongside conventional fuels without the need for new infrastructure. Thus, understanding the interaction of GTL fuels with modern engines, and aftertreatment systems, is important. The current study investigates potential benefits of GTL fuel in respect of diesel particulate filters (DPF). Experiments were conducted on a Euro 4 TDI engine, comparing the DPF response to two different fuels, normal diesel and GTL fuel. The investigation focused on the accumulation and regeneration behavior of the DPF. Results indicated that GTL fuel reduced particulate formation to such an extent that the regeneration cycle was significantly elongated, by ∼70% compared with conventional diesel. Thus, the engine could operate for this increased time before the DPF reached maximum load and regeneration was needed.

The objective of this paper is to present a simulation model for controlling combustion phasing in order to avoid knock in turbocharged SI engines. An empirically based knock model was integrated in a one-dimensional simulation tool. The empirical knock model was optimized and validated against engine tests for a variety of speeds and λ. This model can be used to optimize control strategies as well as design of new engine concepts. The model is able to predict knock onset with an accuracy of a few crank angle degrees. The phasing of the combustion provides information about optimal engine operating conditions.

This paper presents a prospective combustion study about dilution effects on turbocharged SI engine at full load. It proposes a comparative analysis between lean burn and cooled exhaust gas recirculation (EGR) operation as knock improvement artifice in substitute of enrichment. The study was led on a four cylinder 2L engine on stationary test bench. A specific EGR circuit was designed in order to achieve high control of the temperature and mass flow of the recirculated gas. Thanks to instantaneous pressure cylinder transducers, a combustion analysis was carried out using an home-made code. 1-D simulations (WAVE code) were used to complete the analysis on volumetric efficiency and turbocharger behaviour. A real advantage of cooled EGR was observed in the study compared to lean burn or enrichment in terms of performance, heat exchange and specific fuel consumption.

Direct Injection Spark Ignition (DISI) engines are known to be sensitive to injector fouling. To evaluate the effectiveness of detergent additives and the influence of fuel parameters on injector fouling, a new DISI engine test has been developed, using a 2.0 l stoichiometric homogeneous DI engine on a test bench. Severe engine running conditions have been found to lead to a high amount of deposits on the injector nozzle over a short period of time (“one day” procedure). Injector fouling is measured using a fuel flow measurement procedure representative of injector operating conditions (opening time and pressure). This procedure has proved to be reliable and repeatable with different gasoline fuels and additives being evaluated. The influence of the base fuel and the effect of the composition and the dosages levels of detergent additives (keep-clean and clean-up properties) are demonstrated with the test method.

Certain diesel fuel specification properties are considered to be environmental parameters according to the European Fuels Quality Directive (FQD, 2009/EC/30) and previous regulations. These limits included in the EN 590 specification were derived from the European Programme on Emissions, Fuels and Engine Technologies (EPEFE) which was carried out in the 1990’s on diesel vehicles meeting Euro 2 emissions standards. These limits could potentially constrain FAME blending levels higher than 7% v/v. In addition, no significant work has been conducted since to investigate whether relaxing these limits would give rise to performance or emissions debits or fuel consumption benefits in more modern vehicles. The objective of this test programme was to evaluate the impact of specific diesel properties on emissions and fuel consumption in Euro 4, Euro 5 and Euro 6 light-duty diesel vehicle technologies.

Fatigue life predictions using the strain-life method are used in the design of modern light weight vehicle, for the complex loading that occur with the structural durability tests that these vehicles undergo. The accuracy of these predictions is dependent upon the many factors; geometry, loads & materials etc. This paper details a new procedure to ensure the quality and accuracy of the material parameters for the fatigue life prediction software. The material parameters for the solver are obtained by performing strain-controlled fatigue tests. The geometry of the coupons tested is determined by size and thickness of the material specimen that they are machined from and the loading regime in the test. Detailed data analyzed is conducted on these tests and the parameters that are used as input into the CAE strain-life fatigue prediction software are generated.

The purpose of this work was to gain a fundamental understanding of which fuel property parameters are responsible for particulate emission characteristics, associated with key intermediate behavior in the engine cylinder such as the fuel film and insufficient mixing. Accordingly, engine tests were carried out using various fuels having different volatility and chemical compositions under different coolant temperature conditions. In addition, a fundamental spray and film visualization analysis was also conducted using a constant volume vessel, assuming the engine test conditions. As for the physical effects, the test results showed that a low volatility fuel displayed high particulate number (PN) emissions when the injection timing was advanced. The fundamental test clearly showed that the amount of fuel film on the impingement plate increased under such operating conditions with a low volatility fuel.

In light of increasingly stringent CO2 emission targets, Original Equipment Manufacturers (OEM) have been driven to develop engines which deliver improved combustion efficiency and reduce energy losses. In spark ignition engines one strategy which can be used to reach this goal is the full utilization of fuel octane number. Octane number is the fuel´s knock resistance and is characterized as research octane number (RON) and motor octane number (MON). Engine knock is caused by the undesired self-ignition of the fuel air mixture ahead of the flame front initiated by the spark. It leads to pressure fluctuations that can severely damage the engine. Modern vehicles utilize different strategies to avoid knock. One extreme strategy assumes a weak fuel quality and, to protect the engine, retards the spark timing at the expense of combustion efficiency. The other extreme carefully detects knock in every engine cycle and retards the spark timing only when knock is detected.

Stringent regulations on fuel economy have driven major innovative changes in the internal combustion engine design. (E.g. CAFE fuel economy standards of 54.5 mpg by 2025 in the U.S) Vehicle manufacturers have implemented engine infrastructure changes such as downsizing, direct injection, higher compression ratios and turbo-charging/super-charging to achieve higher engine efficiencies. Fuel properties therefore, have to align with these engine changes in order to fully exploit the possible benefits. Fuel octane number is a key metric that enables high fuel efficiency in an engine. Greater resistance to auto-ignition (knock) of the fuel/air mixture allows engines to be operated at a higher compression ratio for a given quantity of intake charge without severely retarding the spark timing resulting in a greater torque per mass of fuel burnt. This attribute makes a high octane fuel a favorable hydrocarbon choice for modern high efficiency engines that aim for higher fuel economy.

In recent years, there has been rapid progress in characterizing the detailed chemical kinetics associated with the oxidation of liquid hydrocarbons and their blends. However adding these fuel models to the industrial engineer's toolkit has proven a major challenge due to issues associated with high CPU cost and the poor suitability of many of the most promising and well known fuel models to IC engine applications. This paper demonstrates the state-of-the-art in the analysis and modelling of current and future transportation fuels or fuel blends for internal combustion engine applications. First-of-all, a benchmarking of eleven representative fuel models (39 to 1034 species in size) is carried out at engine/engine-like operating conditions by adopting the standard Research Octane and Cetane Number test data for comparison. Next, methods to construct a fuel model for a commercial fuel are outlined using a simple, yet robust surrogate mapping technique.

Reported in the current paper is a study into the cycle efficiency effects of utilising a complex valvetrain mechanism in order to generate variable in-cylinder charge motion and therefore alter the dilution tolerance of a Direct Injection Spark Ignition (DISI) engine. A Jaguar Land Rover Single Cylinder Research Engine (SCRE) was operated at a number of engine speeds and loads with the dilution fraction varied accordingly (excess air (lean), external Exhaust Gas Residuals (EGR) or some combination of both). For each engine speed, load and dilution fraction, the engine was operated with either both intake valves fully open - Dual Valve Actuation (DVA) - or one valve completely closed - Single Valve Actuation (SVA) mode. The engine was operated in DVA and SVA modes with EGR fractions up to 20% with the excess air dilution (Lambda) increased (to approximately 1.8) until combustion stability was duly compromised.

An experimental investigation is carried out on the effect of Swirl and Tumble on turbulence and combustion characteristics in four-valve spark ignition engines. This study is conducted on an optically accessed single cylinder research engine. The in-cylinder motion is varied by means of flow-control baffle located between the intake manifold and the cylinder head. Several baffle sizes and shapes have been designed to induce various in-cylinder flow fields. The equivalent angular speed of the tumble and swirl vortices, occurring inside the cylinder, are determined from Laser Doppler Velocimetry. Comparisons with measurements from a conventional steady flow rig which measures air motion speed with a paddle wheel anemometer are presented and show a good correlation between the two measurement techniques.

In a joint research project between industrial companies and a number of research institutes, nitrogen oxide conversion in oxygen containing exhaust gas has been investigated according to the following procedure Basic investigations of elementary steps of the chemical reaction Production and prescreening of different catalytic material on laboratory scale Application oriented screening of industrial catalyst material Catalyst testing on a lean bum gasoline engine, passenger car diesel engines (swirl chamber and DI) and on a DI truck engine Although a number of solid body structures show nitrogen oxide reduction by hydrocarbons, only noble metal containing catalysts and transition metal exchanged zeolites gave catalytic efficiencies of industrial relevance. A maximum of 25 % NOx reduction was found in the European driving cycle for passenger cars, about 40 % for truck engines in the respective European test.