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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.

Mopeds are popular means of transportation, particularly in southern Europe and in eastern and southern Asia. The relative importance of their emissions increases in urban environments which host large fleets of mopeds. In Naples, for example, mopeds make a considerable contribution to HC emissions (about 53%), although the percentage of mopeds (12.4%) in the total circulating fleet is lower than that of other vehicle categories [1]. This study presents a method for analysing the influence of kinematic parameters on the emission factors of mopeds during the “cold-start” and “hot” phases of elementary kinematic sequences (speed-time profiles between two successive stops). These elementary sequences were obtained through appropriate fragmentation of complex urban driving cycles. In a second step, we show how to estimate, for the whole cycle, the duration of the cold phase and the relevant time-dependence function.

Detailed chemistry and turbulence-chemistry interaction need to be properly taken into account for a realistic combustion simulation of IC engines where advanced combustion modes, multiple injections and stratified combustion involve a wide range of combustion regimes and require a proper description of several phenomena such as auto-ignition, flame stabilization, diffusive combustion and lean premixed flame propagation. To this end, different approaches are applied and the most used ones rely on the well-stirred reactor or flamelet assumption. However, well-mixed models do not describe correctly flame structure, while unsteady flamelet models cannot easily predict premixed flame propagation and triple flames. A possible alternative for them is represented by transported probability density functions (PDF) methods, which have been applied widely and effectively for modeling turbulent reacting flows under a wide range of combustion regimes.

Methane abatement in the exhaust gas of natural gas engines is much more challenging in respect to the oxidation of other higher order hydrocarbons. Under steady state λ sweep, the methane conversion efficiency is high at exact stoichiometric, and decreases steeply under both slightly rich and slightly lean conditions. Transient lean to rich transitions can improve methane conversion at the rich side. Previous experimental work has attributed the enhanced methane conversion to activation of methane steam reforming. The steam reforming rate, however, attenuates over time and the methane conversion rate gradually converges to the low steady state values. In this work, a reactor model is established to predict steady state and transient transition characteristics of a three-way catalyst (TWC) mounted in the exhaust of a natural gas heavy-duty engine.

In this work, a promising technique, consisting of a liquid Water Injection (WI) at the intake ports, is investigated to overcome over-fueling and delayed combustions typical of downsized boosted engines, operating at high loads. In a first stage, experimental tests are carried out in a spark-ignition twin-cylinder turbocharged engine at a fixed rotational speed and medium-high loads. In particular, a spark timing and a water-to-fuel ratio sweep are both specified, to analyze the WI capability in increasing the knock-limited spark advance. In a second stage, the considered engine is schematized in a 1D framework. The model, developed in the GT-Power™ environment, includes user defined procedures for the description of combustion and knock phenomena. Computed results are compared with collected data for all the considered operating conditions, in terms of average performance parameters, in-cylinder pressure cycles, burn rate profiles, and knock propensity, as well.

The flapping flight is advantageous for its superior maneuverability and much more aerodynamically efficiency for the small size UAV when compared to the conventional steady-state aerodynamics solution. Especially, it is appropriate for the Micro-air-vehicle (MAV) propulsion system, where the flapping wings can generate the required thrust. This paper investigated such solution, based on the piezoelectric patches, which are attached to the flexible plates, in combination with an appropriate amplification mechanisms. The numerical and experimental flow analyses have been carried out for the piezoelectric flapping plate, in order to characterize the fluid structure interaction induced by the swinging movement of the oscillating plate.

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.

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.

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.

The present work deals with the study of the dynamic behavior of a commercial injector subject to multiple injection strategy. The global spray characteristics have been investigate as well. These studies have been carried out using two numerical codes opportunely modified in order to better simulate the injection process. Comparisons between simulation results and experimental investigations have been made in order to test the reliability of the models. This paper aims at characterizing the macro and microscopic behavior of high pressure Diesel sprays generated by a common rail injector. If it is possible, purpose of this research is to validate and to extend the different correlations available in literature to the case of sprays generated by common rail injectors, especially at high injection pressures.

A PC-programmable electronic control unit (PECU), able to manage both conventional and future electronic injection systems to make a fixed number of consecutive injections (1 to 5 or more) controlling the injection pressure and the injection pulses duration as well as the separation time or dwell in between was used to study the behaviour of a Bosch common rail injection system both on dynamic spray bench and on engine test bench. The PECU allowed a reduction in the dwell time between consecutive injection pulses from the current value of 1800 μs to 500 μs. Photographic sequences of a five holes mini-sac nozzle making five consecutive injections at 400 - 800 and 1200 bar respectively were taken at ambient pressure and temperature. They showed that both spray penetration and cone angle at all operative conditions are very uniform and stable.

A chemical and physical characterization of particulate emitted in undiluted exhaust of single cylinder direct injection (D.I.) diesel engine was made by an optical technique. On-line scattering and extinction measurements in the spectral range from 200 to 500nm were carried out in the exhaust ofthe engine operating under steady-state conditions. These measurements provided a useful tool for the comprehension of chemical and physical structure of the particulate. They allowed the evaluation in real time of the size, the concentration and also the optical properties. Preliminary results of size and mass concentration of particulate are presented. A good agreement was observed comparing the results with those obtained by gravimetric measurements, TEM and X-ray diffraction. HIGH EFFICENCY OF DIESEL ENGINES and their ability to burn heavy fuels make them ofgreat interest in the transportation field.

Ammonia and hydrogen can be produced from water, air and excess renewable electricity (Power-to-fuel) and are therefore a promising alternative in the transition from fossil fuel energy to cleaner energy sources. An Homogeneous-Charge Compression-Ignition (HCCI) engine is therefore being studied to use both fuels under a variable blending ratio for Combined Heat and Power (CHP) production. Due to the high auto-ignition resistance of ammonia, hydrogen is required to promote and stabilize the HCCI combustion. Therefore the research objective is to investigate the HCCI combustion of varying hydrogen-ammonia blending ratios in a 16:1 compression ratio engine. A specific focus is put on maximizing the ammonia proportion as well as minimizing the NOx emissions that could arise from the nitrogen contained in the ammonia. A single-cylinder, constant speed, HCCI engine has been used with an intake pressure varied from 1 to 1.5 bar and with intake temperatures ranging from 428 to 473 K.

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.

Transport activities contribute significantly to air pollution. For this reason any policy or plan, carried out by administration or institution, requires the assessment of its impact on the emissions. To assess the overall pollutant production from transport, it is necessary to calculate emission factors. For this aim several methods exist which only use the average speed of the traffic stream, which can be theoretically obtained by vehicles flow and density on the road. Recently, a new statistical approach has been developed capable to consider more attributes than the simple mean speed to characterize driving behaviour, not only in the determination of driving cycles but also in the emission modelling. In this context, a meso scale emission model, named KEM, Kinematic Emission Model, able to calculate emission factor was developed. However, it is necessary to consider that the input to this model is, in any case, the driving cycle.

This paper presents results of an experimental investigation on a flexible port dual fuel injection using different ethanol to gasoline mass fractions. A four stroke, two cylinder turbocharged SI engine was used for the experiments. The engine speed was set at 3000 rpm, tests were carried out at medium-high load and two air-fuel-ratio. The initial reference conditions were set running the engine, fueled with full gasoline at the KLSA boundary, in accordance with the standard ECU engine map. This engine point was representative of a rich mixture (λ=0.9) in order to control the knock and the temperature at turbine inlet. The investigated fuels included different ethanol-gasoline mass fractions (E10, E20, E30 and E85), supplied by dual injection within the intake manifold. A spark timing sweep, both at stoichiometric and lean (λ=1.1) conditions, up to the most advanced one without knock was carried out.

To check if an unconventional fuel can be burned in an engine, monitoring the stability in terms of composition is mandatory. When the composition of a conventional fuel cannot be measured for practical reason, it can be approximated using the API (American Petroleum Institute) relations (Riazi-Daubert) linking the hydrocarbon group fractions with well-chosen properties. These relations cover only the paraffin (coupling iso and normal), naphthene and aromatic (PNA) groups as they were developed for conventional fuels presenting neglected amounts of olefins and oxygenates. Olefins and oxygenates can be present in unconventional fuels. This paper presents a methodology applicable to any unconventional fuel to build a model to estimate the n-paraffin, iso-paraffin, olefin, naphthene, aromatic and oxygenate (PIONAOx) composition. The current model was demonstrated for an automotive shredder residues (ASR)-derived gasoline-like fuel (GLF).

In-cylinder cycle-resolved LDV measurements have been made in a diesel engine having a high-squish re-entrant combustion chamber with compression ratio of 21:1. The engine has been motored in the range of 1000 to 3000 rpm thanks to the use of self-lubricating seeding particles. Conventional ensemble-averaging and filtering techniques have been used for analyzing instantaneous velocity data obtained at two points along a diameter located in a horizontal plane at 5 mm below the engine head. The dependence of the mean motion and turbulence on engine speed has been evaluated. The effect of cut-off frequency selection on turbulence values has been also analyzed. Moreover, the Kolmogorov's -5/3 power domain has been investigated in detail by spectral analysis on the instantaneous velocity data.

Thrust vectoring is an interesting propulsion solution in aeronautic applications due to its fast response, improving aircraft's performance for take-off, landing and flight, and enabling Short/Vertical Take-Off and Landing (S/VTOL). In this context, an attempt to design a radically new concept of thrust vectoring nozzle is in current development. This novel nozzle, called ACHEON, bases the jet deviation control on the interaction of two primary jets of different velocities, where the one with higher velocity entrains the one with lower velocity. Two cylindrical walls are positioned after the two air jets mixing. If the inlet conditions are not symmetric, the Coanda effect on the walls forces the resulting air jet to divert from the symmetry axis. This paper shows the experimental pressure distribution along the Coanda wall for different inlet.

The use of biodiesel or oxygenated fuels from renewable sources in diesel engines is of particular interest because of the low environmental impact that can be achieved. The present paper reports results of an experimental investigation performed on a light duty diesel engine fuelled with biodiesel, gasoline and butanol mixed, at different volume fractions, with mineral diesel. The investigation was performed on a turbocharged DI four cylinder diesel engine for automotive applications equipped with a common rail injection system. Engine tests were carried out at 2500 rpm, 0.8 MPa of brake mean effective pressure selecting a single injection strategy and performing a parametric analysis on the effect of combustion phasing and oxygen concentration at intake on engine performance and exhaust emissions. The experiments demonstrated that the fuel properties have a strong impact on soot emissions.