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Technical Paper

Influence of a Swirling Air Flow on an Evaporating Diesel Spray from a Common Rail Injection System under Realistic Engine Conditions

2007-09-16
2007-24-0021
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.
Technical Paper

Experimental and Numerical Analyses of Performances and Noise Emission of a Common Rail Light Duty D.I. Diesel Engine

2007-09-16
2007-24-0017
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.
Technical Paper

Experimental Investigation of a Spray from a Multi-jet Common Rail Injection System for Small Engines

2005-09-11
2005-24-090
This paper illustrates the results of an experimental investigation on the liquid fuel spray from a multi-jet common rail injection system both under non evaporative and evaporative conditions. Tests have been taken using a 5 hole, 0.13 mm diameter, 150° spray angle, micro-sac nozzle having a flow rate of 270 cm3/30 sec@10 MPa exploring different injection strategies. Experiments have been taken, under non evaporative conditions, injecting the fuel within stagnant inert gas, at different density, in a high-pressure optically-accessible cylindrical vessel with three large quartz windows. Under evaporative conditions, the experiments have been taken within a crank-case scavenged single-cylinder 2-stroke direct injection Diesel engine provided of optical accesses to the combustion chamber. It allows to study the fuel injection process under thermodynamic conditions similar to those currently reached in modern direct injection diesel engines.
Technical Paper

Some Insight on Premixed Combustion in Diesel Engine With Late Injection: The Influence of Air and Injection Parameters

2005-09-11
2005-24-047
Aim of the present paper was an evaluation of the importance of some engine parameters (intake gas flow and injection parameters) on the approach of Premixed Low Temperature Combustion (PLTC) conditions with the same efficiency of a conventional diesel cycle and ultra-low pollutant emissions. The results have demonstrated that the control of PLTC mode is very difficult and the engine parameters play a critical role on the exhaust pollutant emissions, indicating that further massive research activities are needed to reach reliable practical applications.
Technical Paper

Multidimensional Modeling of Advanced Diesel Combustion System by Parallel Chemistry

2005-04-11
2005-01-0201
In the present paper the combustion process in a modern second generation Common Rail Diesel engine for light duty application is experimentally and numerically investigated. An improved version of the KIVA3V-Release 2 code was used for the simulations. To model the combustion process, a detailed kinetic scheme involving 57 species and 290 equations, based on the n-heptane combustion, was used, interfacing the KIVA3V code with the CHEMKIN-II chemistry package. The full set of equations is concurrently solved in each computational cell by different solvers with the final aim of obtaining a locally adaptative code: local choices are undertaken in terms of time steps as well as in terms of the employed solvers. To reduce computational time, the code was parallelized: this parallelization is mainly focused on the chemical subroutines, considering that they are responsible for more than the 95% of the computing.
Technical Paper

Laser Diagnostic of Particles Exhaust Emission from Advanced Diesel Combustion Systems

2005-04-11
2005-01-0188
The effect of fuel injection strategy and charge dilution on NOx and soot emissions has been investigated with a modern DI diesel engine. Particulate mass has been measured by a standard smoke meter and soot particles have been characterized by means of time-resolved Laser Induced Incandescence (LII) at the exhaust of the engine. Two steady-state test points have been selected, representative of low and medium load conditions. The influence of the different engine management strategies has been assessed, highlighting the potential of unconventional operating modes to meet forthcoming emission limits.
Technical Paper

Downsizing of Common Rail D.I. Engines: Influence Of Different Injection Strategies on Combustion Evolution

2003-05-19
2003-01-1784
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.
Technical Paper

Potentiality of the Modern Engines Fed by New Diesel Fuels to Approach the Future European Emission Limits

2002-10-21
2002-01-2826
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).
Technical Paper

In-cylinder Soot Evolution Analysis in a Transparent Research DI Diesel Engine Fed by Oxygenated Fuels

2002-10-21
2002-01-2851
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.
Technical Paper

Combustion Process Management in Common Rail DI Diesel Engines by Multiple Injection

2001-09-23
2001-24-0007
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.
Technical Paper

Combustion Chamber Design Effects on D.I. Common Rail Diesel Engine Performance

2001-09-23
2001-24-0005
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.
Technical Paper

Design of a small displacement transparent research engine equipped with a common-rail diesel injection system

2001-09-23
2001-24-0021
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.
Technical Paper

Further knowledge on effects of fuels quality changes on emission potential of common-rail D.I. diesel engine

2001-09-23
2001-24-0042
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.
Technical Paper

Diesel Engines Fueled by Wood Pyrolysis Oil: Feasibility and Perspectives

2001-09-23
2001-24-0041
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.
Technical Paper

Running Light-Duty DI Diesel Engines with Wood Pyrolysis Oil

2000-10-16
2000-01-2975
This paper reports on the first successful tests performed on a production D.I. Diesel engine using wood pyrolysis oil (WPO). As reported in literature, any attempt to directly replace Diesel fuel with WPO required extensive modifications to the engine injection system, in order to overcome the intrinsic limits of the oil (poor self-ignition, high acidity and viscosity): new materials, additional pilot injection systems, careful procedures of start-up and shutdown were needed to obtain acceptable operation. Aim of the present work was to assess the limits of utilization of WPO in a strictly stock engine. Therefore, while no modifications at all were carried out on the engine, the efforts were addressed to make the WPO compatible with light-duty Diesel engines. Several long-running tests were performed on a single-cylinder engine, with: blends of WPO with different percentage of oxygenated compounds micro-emulsions of WPO in Diesel fuel standard (commercial) Diesel fuel.
Technical Paper

Combustion Behavior Analysis in a Transparent Research Engine Equipped with a Common Rail Diesel Injection System

2000-06-19
2000-01-1825
This paper describes a preliminary characterization of in-cylinder spray and combustion behavior from a high-pressure common rail injection system. The engine used in the tests was a single-cylinder optical research diesel engine, adequately developed in a full-fired version, equipped with a common rail injection system. An elongated piston allows for the optical access to the combustion chamber for diagnostic applications. Characteristic of the optical engine is the availability to investigate different combustion system designs due to an interchangeable head-cylinder group. The system configuration tested in the present work corresponds to a four-cylinder engine of 1930 cc of displacement that is representative in the class of light duty d.i. diesel engine. Spray and combustion evolutions were visualized through a high-speed CCD camera synchronized with a copper vapor laser acting as light source.
Technical Paper

Experimental Investigation on High-Quality Diesel Fuels Effects in a Light Duty CR Diesel Engine

2000-06-19
2000-01-1911
In this paper some preliminary results on the emission performance of a modern CR DI diesel engine running on reformulated diesel fuels are discussed. The engine employed in the tests was a Fiat M724 1910cc, installed on Alfa Romeo 156 1.9 JTD. Modern injection systems can modify the spray structure with respect to a spray of a classical rotary injection pump so the well-consolidated knowledge on the correlation between fuel parameters and pollutant emissions may not be valid for the new generation of DI diesel engines. Two high quality fossil fuels and a synthetic fuel were selected for the tests. Tests were directed to analyze the relative influence on exhaust emissions between injection parameters and fuel quality. One engine test point (2000 rpm × 2 bar of b.m.e.p.) was chosen, with different setting of injection pressure, EGR ratio and pilot injection activation.
Technical Paper

Potentiality of Oxygenated Synthetic Fuel and Reformulated Fuel on Emissions from a Modern DI Diesel Engine

1999-10-25
1999-01-3595
This paper presents the performances of a modern DI diesel engine, equipped with a Common Rail injection system, fed on blends of an advanced diesel fuel (base fuel) and Diethylene-Glycol-Dimethyl-Ether (Diglyme - C6H14O3). The base fuel was a reformulated diesel fuel with low aromatic and sulfur content. Three blends with different volumetric percentage of Diglyme (10, 20 and 30%) in the base fuel were prepared and tested. The engine was a FIAT M724, installed in a Alfa Romeo 156 1.9 JTD, with a Bosch Common Rail injection system (EDC-15C). At the exhaust of the engine, soot, NOx, HC, CO, and CO2 were measured. The experiments represent the potential of diesel reformulation technology with synthetic fuels coupled with the new diesel technology generation.
Technical Paper

New Trends in Combustion System Design of Light Duty Diesel Engines Inferred by Threedimensional C.F.D. Computations

1998-10-19
982461
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.
Technical Paper

Evaluation of Combustion Behavior and Pollutants Emission of Advanced Fuel Formulations by Single Cylinder Engine Experiments

1998-10-19
982492
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.
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