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An Experimental Analysis on Diesel/n-Butanol Blends Operating in Partial Premixed Combustion in a Light Duty Diesel Engine

2012-06-18
This paper reports results of an experimental investigation performed on a commercial diesel engine supplied with fuel blends having low cetane number to attain a simultaneous reduction in NOx and smoke emissions. Blends of 20% and 40% of n-butanol in conventional diesel fuel have been tested, comparing engine performance and emissions to diesel ones. Taking advantage of the fuel blend higher resistance to auto ignition, it was possible to extend the range in which a premixed combustion is achieved. This allowed to match the goal of a significant reduction in emissions without important penalties in fuel consumption. The experimental activity was carried on a turbocharged, water cooled, 4 cylinder common rail DI diesel engine. The engine equipment included an exhaust gas recirculation system controlled by an external driver, a piezo-quartz pressure transducer to detect the in-cylinder pressure signal and a current probe to acquire the energizing current to the injector.
Technical Paper

MonteCarlo Techniques in Thermal Analysis – Design Margins Determination Using Reduced Models and Experimental Data

2006-07-17
2006-01-2113
In the paper several application techniques of MonteCarlo (MC) method applied to thermal analysis of space vehicles are presented. Although these methods are widely used in other engineering domains, their introduction to the thermal one is quite recent and not fully developed in the industrial practice. This paper aims at showing that, even without demanding computation resources (all what presented has been obtained with a single processor PC) MonteCarlo analysis techniques, in a preliminary design phase, can support and integrate engineering judgment of the thermal designer. In particular, it is exploited the applicability of the method to reduced thermal models, with a clear advantage in terms of computation time. An original approach is proposed, and results are shown. The papers shows the applicability of the MC method to the case when experimental data of the uncertain parameters are available, using the bootstrap re-sampling techniques.
Technical Paper

Effect of the air density on the evolution and mixing properties of a GDI swirled spray

2001-09-23
2001-24-0048
A swirl injector for GDI application was used to inject an iso-octane spray in a quiescent chamber, to study the effect of the air density on the spray behavior. Stroboscopic images are recorded at different delays from the injection trigger to study the spray shape and structure. The temporal evolution of different spray parameters, length, width, angle, volume, instantaneous global air-fuel ratio, is calculated from the images. The effect of the increasing air density is to shorten the time and length scale of the spray evolution.
Technical Paper

A Method for the Characterization of Off-Road Terrain Severity

2006-10-31
2006-01-3498
Highway and roadway surface measurement is a practice that has been ongoing for decades now. This sort of measurement is intended to ensure a safe level of road perturbances. The measurement may be conducted by a slow moving apparatus directly measuring the elevation of the road, at varying distance intervals, to obtain a road profile, with varying degrees of resolution. An alternate means is to measure the surface roughness at highway speeds using accelerometers coupled with high speed distance measurements, such as laser sensors. Vehicles out rigged with such a system are termed inertial profilers. This type of inertial measurement provides a sort of filtered roadway profile. Much research has been conducted on the analysis of highway roughness, and the associated metrics involved. In many instances, it is desirable to maintain an off-road course such that the course will provide sufficient challenges to a vehicle during durability testing.
Technical Paper

CFD Modelling of Gasoline Sprays

2005-09-11
2005-24-086
A comprehensive model for sprays emerging from high pressure swirl injectors for GDI engine application has been developed. The primary and secondary atomization mechanism as well as the evaporation process both in standard and superheated conditions are taken into account. The spray modelling after the injection is based on the Liquid Instability Sheet Atomization (LISA) approach, modified to correctly predict the liquid sheet thickness at the breakup length. The effect of different values of the superheat degree on evaporation and impact on the spray distribution and fuel-air mixing is analyzed. Comparisons with experimental data show good agreements under atmospheric conditions and with different superheated degrees, while some discrepancies occur under higher ambient pressures.
Technical Paper

Kinetic Modelling Study of Octane Number and Sensitivity of Hydrocarbon Mixtures in CFR Engines

2005-09-11
2005-24-077
Aim of this work is to present and discuss the possibility and the limits of two zone models for spark-ignition engines using a detailed kinetic scheme for the characterization of the evolution of the air-fuel mixture, while an equilibrium approach is used for the burnt zone. Simple experimental measurements of knocking tendency of different fuels in ideal reactors, such as rapid compression machines and shock tube reactors, cannot be directly used for the analysis of octane numbers and sensitivity of hydrocarbon mixtures. Thus a careful investigation is very useful, not only of the combustion chamber behavior, including the modelling of the turbulent flame front propagation, but also of the fluid dynamic behavior of the intake and exhaust system, accounting for the volumetric efficiency of the engine.
Technical Paper

Progress in Diesel HCCI Combustion Within the European SPACE LIGHT Project

2004-06-08
2004-01-1904
The purpose of the European « SPACE LIGHT » (Whole SPACE combustion for LIGHT duty diesel vehicles) 3-year project launched in 2001 is to research and develop an innovative Homogeneous internal mixture Charged Compression Ignition (HCCI) for passenger cars diesel engine where the combustion process can take place simultaneously in the whole SPACE of the combustion chamber while providing almost no NOx and particulates emissions. This paper presents the whole project with the main R&D tasks necessary to comply with the industrial and technical objectives of the project. The research approach adopted is briefly described. It is then followed by a detailed description of the most recent progress achieved during the tasks recently undertaken. The methodology adopted starts from the research study of the in-cylinder combustion specifications necessary to achieve HCCI combustion from experimental single cylinder engines testing in premixed charged conditions.
Technical Paper

Application of the CTC Model to Predict Combustion and Pollutant Emissions in a Common-Rail Diesel Engine Operating with Multiple Injections and High EGR

2012-04-16
2012-01-0154
Multiple injections and high EGR rates are now widely adopted for combustion and emissions control in passenger car diesel engines. In a wide range of operating conditions, fuel is provided through one to five separated injection events, and recirculated gas fractions between 0 to 30% are used. Within this context, fast and reliable multi-dimensional models are necessary to define suitable injection strategies for different operating points and reduce both the costs and time required for engine design and development. In this work, the authors have applied a modified version of the characteristic time-scale combustion model (CTC) to predict combustion and pollutant emissions in diesel engines using advanced injection strategies. The Shell auto-ignition model is used to predict auto-ignition, with a suitable set of coefficients that were tuned for diesel fuel.
Technical Paper

Development of a CFD Approach to Model Fuel-Air Mixing in Gasoline Direct-Injection Engines

2012-04-16
2012-01-0146
Direct-injection represents a consolidated technology to increase performance and efficiency in spark-ignition engines. It reduces the knock tendency and makes engine downsizing possible through the use of turbocharging. Better control of CO and HC emissions at cold-start is also ensured since there is no wall-impingement in the intake port. However, to take advantages of all the theoretical benefits derived from GDI technology, detailed investigations of both fuel-air mixing and combustion processes are necessary to extend the stratified charge operations in the engine map and to reduce soot emissions, that are now severely regulated by emission standards. In this work, the authors developed a CFD methodology to investigate and optimize the fuel-air mixing process in direct-injection, spark-ignition engines. The Eulerian-Lagrangian approach is used to model the evolution of the fuel spray emerging from a multi-hole injector.
Technical Paper

Does European Type Approval Procedure Encourage the Diffusion of Hybrid and Other Low Emission Vehicles?

2010-05-05
2010-01-1445
European Type approval procedure defines a synthetic driving cycle (the NEDC) over which one vehicle per type has to be tested. Euro 1, 2, 3, 4 and 5 differ (beside vehicle preconditioning and warm-up procedures introduced since Euro 3) only because limits for the different pollutants have been progressively lowered. This paper analyses through a number of experimental tests on spark-ignition cars, a hybrid and a conventional vehicle, the driving conditions responsible for most of the emissions and assesses how such conditions are reproduced by the type approval test. The engine conditions mostly responsible for emissions are: warm-up phase, full loads and transients. Only the warm-up is well covered by the NEDC for vehicles with more than 35 kW/ton power-weight ratio.
Technical Paper

A 2D Model for Tractor Tire-Soil Interaction: Evaluation of the Maximum Traction Force and Comparison with Experimental Results

2011-04-12
2011-01-0191
The paper investigates the interaction between soil and tractor tires through a 2D numerical model. The tire is schematized as a rigid ring presenting a series of rigid tread bars on the external circumference. The outer profile of the tire is divided into a series of elements, each one able to exchange a normal and a tangential contact force with the ground. A 2D soil model was developed to compute the forces at the ground-tire interface: the normal force is determined on the basis of the compression of the soil generated by the sinking of the tire. The soil is modeled through a layer of springs characterized by two different stiffness for the loading (lower stiffness) and unloading (higher stiffness) condition. This scheme allows to introduce a memory effect on the soil which results stiffer and keeps a residual sinking after the passage of the tire. The normal contact force determines the maximum value of tangential force provided before the soil fails.
Technical Paper

A preliminary study to evaluate emissions factors by real and micro simulated driving cycle

2009-09-13
2009-24-0150
Transport activities contribute significantly to the air pollution and its impact on emissions is a key element in the evaluation of any transport policy or plan. Calculation of emissions has therefore gained institutional importance in the European Community. To obtain emission factors several methods make use of only vehicle mean velocity, which can be easily obtained by vehicle flow and density in the road. Recently in ARTEMIS project by Rapone et al. (2005–2007) a meso scale emission model, named KEM (Kinematic Emission Model), able to calculate emission factor has been developed. This model is based on a new statistical methodology, capable to consider more attributes than the simple mean speed to characterize driving behaviour. An interesting approach to determine the exact mix of driving cycles is represented by the use of microscopic traffic simulation models that could be used to avoid the very expensive costs of experimental campaigns needed to obtain real driving cycle.
Technical Paper

Preliminary Design of a Bio-Regenerative ECLSS Technological Demo Plant for Air and Water Management

2008-06-29
2008-01-2013
Future human exploration roadmaps involve the development of temporary or permanent outposts on Moon and Mars. The capability of providing astronauts with proper conditions for living and working in extraterrestrial environments is therefore a key issue for the sustainability of those roadmaps, and closed-loop Environment Control and Life Support Systems (ECLSSs) and bio-regenerative plants represent the necessary evolution of current technologies for complying with the challenging requirements imposed. This paper presents the architectural design of a terrestrial plant to be exploited to test and validate air and water management technologies for a biological life support system in a closed environment. The plant includes a crew area and a plant growth area. These two spaces can be considered as either a unique volume or two separated environments with reduced contact, e.g. for plant harvesting or other up-keeping activities.
Technical Paper

Integrated Breathing Model and Multi-Variable Control Approach for Air Management in Advanced Gasoline Engine

2006-04-03
2006-01-0658
The evolution of automotive engines calls for the design of electronic control systems optimizing the engine performance in terms of reduced fuel consumption and pollutant emissions. However, the opportunities provided by modern engines have not yet completely exploited, since the adopted control strategies are still largely developed in a very heuristic way and rely on a number of SISO (Single Input Single Output) designs. On the contrary, the strong coupling between the available actuators calls for a MIMO (Multi Input Multi Output) control design approach. To this regard, the availability of reliable dynamic engine models plays an important role in the design of engine control and diagnostic systems, allowing for a significant reduction of the development times and costs. This paper presents a control-oriented model of the air-path system of today's gasoline internal combustion engines.
Technical Paper

Development and Application of S.I. Combustion Models for Emissions Prediction

2006-04-03
2006-01-1108
The s.i. combustion process and its corresponding pollutant formation are investigated by means of a quasiD approach and a CFD model. This work has been motivated by the need to better understand the reliability of such models and to assess their accuracies with respect to the prediction of engine performances and emissions. An extended dissertation about the fundamental mechanisms governing the pollutant formation in the turbulent premixed combustion which characterizes the s.i. engines is given. The conclusion of such analysis is the definition of a new reduced chemical scheme, based on the application of partial-equilibrium and steady-state assumptions for the radicals and the solution of a transport equation for each specie which is kinetically controlled. For this purpose the CFD code OpenFOAM [1, 2, 3] and the thermo-fluid dynamic code GASDYN [4, 5] have been applied and enhanced.
Technical Paper

A Low Temperature Pathway Operating the Reduction of Stored Nitrates in Pt-Ba/Al2O3 Lean NOx Trap Systems

2006-04-03
2006-01-1368
In this paper the low temperature reduction process of nitrates stored at high temperatures over model Pt-Ba/Al2O3 LNT catalysts using both H2 and C3H6 is analyzed. The results indicate that over the Pt-Ba/Al2O3 catalyst the reduction of stored NOx with both H2 and C3H6 occurs at temperature below those corresponding to their thermal stability. Accordingly, the reduction process occurs through a Pt-catalyzed surface reaction, which does not involve, as a preliminary step, the thermal decomposition of the adsorbed NOx species. The occurrence of such a pathway also requires the co-presence of the storage element and of the noble metal on the same support.
Technical Paper

MAAT Cruiser/Feeder Airship: Connection and Passenger Exchange Modes

2013-09-17
2013-01-2113
In the general framework of the EU FP7 MAAT project, a novel green air transport architecture is under development. The paper presents the possible architectures for the cabin connections and the transfer modalities for people, crew and freight, for to the European project MAAT. Different architectures have been evaluated setting out to cover the structural and propulsive needs and to enable the transport modes between the Cruiser and the Feeders. The different possibilities are discussed conceptually, by considering the advantages and disadvantages of the presented configurations. The bases for future detailed design and research are established, as through such conceptual study the main parameters are identified and found to affect the general design of both airships and their operability. The aim of this paper is to specify the necessary elements, which are necessary to perform the docking operation by taking into account the prescribed Feeder-Cruiser geometries.
Technical Paper

Experimental and Numerical Analyses for the Characterization of the Cyclic Dispersion and Knock Occurrence in a Small-Size SI Engine

2010-09-28
2010-32-0069
In this paper, an experimental and numerical analysis of combustion process and knock occurrence in a small displacement spark-ignition engine is presented. A wide experimental campaign is preliminarily carried out in order to fully characterize the engine behavior in different operating conditions. In particular, the acquisition of a large number of consecutive pressure cycle is realized to analyze the Cyclic Variability (CV) effects in terms of Indicated Mean Effective Pressure (IMEP) Coefficient of Variation (CoV). The spark advance is also changed up to incipient knocking conditions, basing on a proper definition of a knock index. The latter is estimated through the decomposition and the FFT analysis of the instantaneous pressure cycles. Contemporary, a quasi-dimensional combustion and knock model, included within a whole engine one-dimensional (1D) modeling framework, are developed. Combustion and knock models are extended to include the CV effects, too.
Technical Paper

Evolution of the Ride Comfort of Alfa Romeo Cars since 1955 until 2005

2017-03-28
2017-01-1484
The ride comfort of three Alfa Romeo cars, namely Giulietta (1955), Alfetta (1972) and 159 (2005) has been assessed both objectively and subjectively. The three cars belong to the same market segment. The aim is to let young engineers or graduate students understand how technology has evolved and eventually learn a lesson from the assessed trend. A number of cleats have been fixed at the ground and the three cars have traversed such uneven surface. The objective assessment of the ride comfort has been performed by means of accelerometers fixed at the seat rails, additionally a special dummy developed at Politecnico di Milano has been employed. The subjective assessment has been performed by a panel of passengers. The match between objective and subjective ratings is very good. Simple mathematical models have been employed to establish a (successful) comparison between experimental and computational results. The ride comfort differs substantially among the cars.
Technical Paper

Increasing Aeronautic Electric Propulsion Performances by Cogeneration and Heat Recovery

2014-09-16
2014-01-2106
Emissions from aviation have become a focus of increasing interest in recent years. The growth of civil aviation is faster than nearly all other economic sectors. Increased demand has led to a higher growth rate in fossil fuels consumption by the aviation sector. Despite more fuel-efficient and less polluting turbofan and turboprop engines, the growth of air travel contributes to increase pollution attributable to aviation. Aircraft are currently the only human-made in situ generators of emissions in the upper troposphere and in the stratosphere. The depletion of the stratosphere's ozone layer by CFCs and related chemicals has underscored the importance of anticipating other potential insults to the ozone layer. Different possible solutions have been advanced to reduce the environmental impact of aviation, such as electrification of ground operations, optimization of airline timetables and airspace usage, limitation of cruise altitude and increased use of turboprop aircrafts.
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