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Technical information on the development of a new Lombardini prechamber diesel engine family, called FOCS, is given. Market requirements in terms of high performance, low fuel consumption, light engine weight and low noise and pollutant emissions have been met. The engine family consists of 2, 3 and 4 cylinder models with 72 mm cylinder bore and with two stroke-length (62, 75 mm) version covering 505 cc, 611 cc, 916 cc and 1222 cc displacement. Comparison of performance and emissions between FOCS 602 and competitive engines nowadays available on the international market is reported.

The optimization of combustion system of a single-cylinder d.i. diesel engine, representative of heavy-duty family, is discussed. The characterization of in-cylinder fluid motion of a conventional straight-sided and a re-entrant combustion chamber, carried out by LDA technique, is presented. Engine tests, using the same chambers and sacless nozzles with different holes diameter and appropriate spray angle, have been performed. Strong reduction of smoke and HC emissions has been obtained, remaining unchanged the engine performance.

A methodological analysis of combustion parameters and pollutant emissions measuring procedures during transient operation of a D.I. T.C. light duty diesel engine was performed. Combustion process was characterized by ignition delay time, combustion pressure peak value and heat release law measurements during the transient ECE 15 schedule on a dynamic test bed with electronic simulation of inertia. The particulate emission was measured every 0.05 s by an I.R. optical method. In addition some correlations, based on pressure cycle and injection law evolution, were implemented in order to calculate instantaneous fuel delivery and transient NOx emission. Some activities were carried out in order to asses the limits of engine configurations ranking performed with steady state measurements of performances and emissions. Strong differences were detected between carbon emission during transient operations and the value obtained by interpolation from a steady state map.

In this paper results on in-cylinder pollutant concentration evolution during combustion of six different oxygenated fuels, in comparison with tetradecane and n-octane combustion, are presented. These four fuels are: Ethylene-Glygol-Dimethylether (monoglyme-C4H10O2), Diethylene-Glygol-Dimethylether (diglyme-C6H14O2), Diethylene-Glycol-Diethylether (diethyldiglycol-C8H18O3), butylether (C8H18O). Two techniques were adopted on a single cylinder direct injection diesel engine: two-color pyrometry for the measurement of in-cylinder soot loading and a fast sampling valve for the measurements of in-cylinder combustion products. In addition, the sampling line downstream of the fast sampling valve was adapted for the in-cylinder aldehyde measurements. The main results obtained provide information about the mechanisms that control soot evolution during diesel combustion.

The aim of the present paper is to provide an insight into the fluid dynamic processes that occur during the air/fuel mixture formation period in direct injection diesel engines. An experimental and numerical investigation has been performed to analyse the mixing process between an evaporating diesel spray and a swirl air flow under realistic engine conditions. Experimental tests have been carried out spraying the fuel within an optically accessible prototype 2-stroke Diesel engine equipped with an external combustion chamber having cylindrical shape. The intake air flow, coming from the engine cylinder, is forced within the combustion chamber by means of a tangential duct generating a well structured swirl flow similar to that developing in a real light duty diesel engine with a high swirl ratio. A micro-sac 5-hole, 0.13 mm diameter, 150° spray angle electro-hydraulic injector supplies the fuel by a common rail injection system able to manage multiple injection strategies.

This paper illustrates a numerical and experimental analysis of performances and overall noise radiated from a common rail light duty diesel engine. The engine was equipped with two different injection systems: an under development low-cost fuel injector and a commercial Bosch one, employed for automotive applications. The injectors behaviour was compared throughout an experimental investigation that was carried out on a naturally aspirated, four strokes, two valves, single cylinder engine (225 cm3 displacement). Both engine performances, pollutant and noise emissions were measured at different operating conditions for two injection strategies. Concerning the acoustic analysis, both structure born and gasdynamic noise contributions were estimated using different experimental techniques.

According to the results of several studies concerning the influence of fuel formulation on exhaust emissions from diesel engines, a new matrix of twelve fuels was tested in a single cylinder DI diesel engine of conventional technology. The matrix was designed by the partners of the FLOLEV research project, partly founded by the E.U., in the framework JOULE III program. The aim of the project is to study the influence on pollutants emission reduction of modern refining process and fuel additivation with some alternative fuels and cetane improvers. The fuel matrix is structured into three sub-matrices. The first sub-matrix is constituted by six fuels which represent different products obtainable with the modern refinery technology. The second and third sub-matrices were designed to test the influence of cetane improver additives and high-oxygenated fuels respectively.

In the present paper some results, obtained by the use of modern numerical C.F.D tools, are presented. In particular, starting from the experimental characterization of a conventional design D.I. diesel engine, the empirical constants of the different submodels were tuned to obtain satisfactory results in some key test conditions. After that, in the same points of the engine performance map, the following parameters were systematically varied: Fuel injection system design and operating conditions Intake swirl level Exhaust gas recirculation level. The influence of each parameter on combustion evolution is discussed and the most promising trend for the engine optimization is presented. Taking into account the model formulations limits, the results obtained suggest, from a theoretical point of view, that “common rail” equipped light duty diesel engines are suitable to meet the future European emission regulations.

In the present paper the KIVA3V code is used to model the behaviour of different combustion chambers, to be used in Common Rail engines with a single displacement lower than 0.5l. Some design parameters have been chosen to evaluate their influence on the combustion patterns. The optimum levels of turbulence and air mean motion have been selected with reference to some specific points of the engine map, managed by mean of multiple injection. Therefore the different combustion chambers geometries have been numerically investigated in terms of fluidynamic behaviour as well as in terms of combustion evolution. After that some chamber geometries, especially suitable for the second-generation common rail engines, have been selected.

This paper describes the project of a "small' single-cylinder direct injection diesel engine (300 cc). It is equipped with optical accesses to analyze the diesel combustion process employing the most recent optical diagnostic techniques. The injection system used is a second-generation common- rail system. The optical accesses are placed on the piston and on the cylinder wall.

The improvements of the solenoid injector and of the Electronic Control Unit of the present Common Rail injection system (C.R.) allow the use of multiple sequential injections. Thanks to this feature this advanced Common Rail system is capable to perform up to five consecutive injections in one engine cycle thus improving control of the combustion process. In particular, in some operating conditions, the activation of a small injection after the main one allows the oxidation of the soot produced in the previous stages of the combustion process, without increasing nitrogen oxide emissions. This paper describes the experimental results obtained with the application of a prototype of this advanced Common Rail system both to a Fiat L4 1.9 JTD 8 valve engine and to a single-cylinder prototype, having the same combustion system and large optical access allowing investigation of the injection and combustion processes.

Conventional methods for combustion gas concentration measurement are typically based on gas sampling, sample treatment and subsequent analysis. These procedures could affect the species concentrations in particular when temporal variations of process parameters are under study. Moreover, in these methods, the concentration measurements are usually performed at standard temperature and pressure. In order to overcome these limitations, in-situ and real-time concentration measurement techniques are needed. In this paper, an in-situ technique with high spatial and temporal resolution, based on ultraviolet-visible absorption spectroscopy, was proposed. This technique allowed the simultaneous determination of NO and OH absolute concentrations inside optically accessible diesel combustion chamber. Temporal and spatial distribution of OH and NO was evaluated.

Aim of this paper was to assess the feasibility of the application of wood pyrolysis oil (WPO) as a fuel for medium-duty Diesel engines. The experimental activity was carried out both on a diesel injection system and on a DI Diesel engine. High-speed visualization was used to highlight the spray characteristics and an instrumented test bench to evaluate engine performance and emissions. No modification was carried out on the engine and the efforts were addressed to make the WPO compatible with engine operation. Accordingly, WPO was not tested as a pure fuel, but in blends with diglyme and in emulsions with Diesel fuel.

This paper reports some results on the emission performance of a CR DI diesel engine burning five model diesel fuels. The fuels were prepared by Agip Petroli S.p.A within the PNRA research program, sponsored by Italian Ministry of Environment and were a base fuel, a synthetic fuel and three oxygenated fuels. The engine employed in the tests was a prototype derived from Fiat M724 1910 cc, installed on Fiat Group class C Cars (1350 kg of mass). The prototype complies with EURO3 regulations. Two test points representative of two zones of ECE15+EUDC test cycle were chosen. Thermodynamic variables, emissions and injection systems parameters were recorded. Tests show the further potential of advanced fuels, obtained by blends of reformulated and oxygenated components, in reducing pollutants emissions.

This paper describes a characterisation of the combustion behaviour in an optical Common Rail diesel engine fed by different advanced fuels, via the application of the two-colour pyrometry technique. The acquired images were processed in order to calculate the instantaneous flame temperature and soot volume fraction. For the measurements, a single test point was chosen as representative of the reference four-cylinder engine performance in the European driven cycle ECE+EUDC. The test point was the 1500 rpm and 22 mm3/stroke of injected fuel volume, correspondent to the engine point of 1500rpm @ 5 bar of BMEP for the 4-cylinder engine of 1.9L of displacement. As general overview, the flame luminosity from combustion of the fuel injected during pilot injection was always below the threshold of sensitivity of the detection system.

This paper reports some results on the performance of an advanced common rail (CR) DI diesel engine burning 12 model diesel fuels. The experiments were carried out within a co-operative research program “NeDeNeF” (New Diesel Engines and New Diesel Fuels), partly sponsored by the Commission of European Communities. Partners of the project with Istituto Motori (IM) were: FEV (Germany), VTT (Finland), NTUA (Greece), Brunel University (UK), Fortum (Finland), LAT (Greece) under the coordination of the IFP (France). The matrix of twelve fuels was prepared by the fuel producer partner (Fortum). The research program of the Diesel Engines and Fuels Department of Istituto Motori aimed at assessing the effect of fuel quality on exhaust emissions. The engine employed in the tests was a Fiat four-cylinder DI CR diesel engine, EURO3 version, of 1.9 litre, installed on Fiat Group class C Cars (1350kg of mass).

This paper refers to the experimental results obtained using two different 4 cylinder diesel engines, with total displacement respectively equal to 1.9l and 1.3l, both equipped with an advanced Common Rail system. An optically accessed prototype engine, having characteristics similar to the four cylinder engine, is used to visualize the in cylinder phenomena. Multidimensional simulations of the combustion and pollutants formation processes are performed, comparing the numerical predictions with the experimental data. By this way, integrating the 3D C.F.D. computations, the visualization techniques of the injection and combustion processes and the field measurements on the real engines, different settings of the multiple injection strategy have been analyzed.

Improvement of combustion system for low emissions of a single cylinder diesel engine is presented. In particular the effects of spray angle, holes diameter and number, compression ratio and combustion chamber geometry on engine performance and emissions are evaluated. The fluid-dynamic behaviour of combustion system is analyzed by LDA technique. Engine tests have been carried out at two engine speed and at different start of combustion. The particulate matter has been analyzed in terms of soluble organic fraction and dry soot.

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.

The fluid-mechanic behaviour of straight-sided and re-entrant chamber geometries has been studied using laser doppler anemometry (LDA) technique. Measurements have been carried out during the compression stroke in a direct injection diesel engine, representative of medium size family, operating at 1000 rpm under motored conditions. The mean motion and turbulence intensity have been computed using a filtering procedure on the LDA data. Using the second version of KIVA code, the air flow field evolution during the same crank angle period has been also computed. To perform proper comparisons between measured and computed values of mean velocity and turbulence intensity, a careful choice of the initial conditions for computations has been performed. Reasonable agreement has been found between computed and measured mean swirl velocities for both combustion chamber geometries tested. On the contrary, the computed turbulence intensities underestimate those measured.