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Viewing 1 to 30 of 37
2011-04-12
Technical Paper
2011-01-1286
Gerardo Valentino, Luigi Allocca, Luca Marchitto
The paper presents results of an experimental investigation of the fluid dynamic processes during the air/fuel mixture formation period between an evaporating diesel spray and swirl air flow under realistic engine conditions. Particle Image Velocimetry (PIV) experiments have been carried out using an optically accessible prototype 2-stroke diesel engine equipped with a swirled combustion chamber. The flow within the chamber assumes a well structured swirl motion, similar to that developing in a real diesel engine, operating at high swirl ratio. The engine has been equipped with a common rail injection system and a solenoid-controlled injector, in use on automotive engines for the European market, able to manage multiple injection strategies. Two injector nozzles have been tested: a micro-sac 5-hole nozzle, 0.13 mm diameter, 150° spray angle and a 7-hole, 0.141 mm diameter, 148° spray angle.
2013-09-08
Technical Paper
2013-24-0020
Enrico Mattarelli, Stefano Fontanesi, Carlo Rinaldini, Gerardo Valentino, Stefano Iannuzzi, Elena Severi, Valeri Golovitchev
Enhanced calibration strategies and innovative engine combustion technologies are required to meet the new limits on exhaust gas emissions enforced in the field of marine propulsion and on-board energy production. The goal of the paper is to optimize the control parameters of a 4.2 dm3 unit displacement marine DI Diesel engine, in order to enhance the efficiency of the combustion system and reduce engine out emissions. The investigation is carried out by means of experimental tests and CFD simulations. For a better control of the testing conditions, the experimental activity is performed on a single cylinder prototype, while the engine test bench is specifically designed to simulate different levels of boosting. The numerical investigations are carried out using a set of different CFD tools: GT-Power for the engine cycle analysis, STAR-CD for the study of the in-cylinder flow, and a customized version of the KIVA-3V code for combustion.
2013-09-08
Technical Paper
2013-24-0066
Cinzia Tornatore, Luca Marchitto, Gerardo Valentino, Stefano Iannuzzi, Simona Merola
In this paper, a high temporal resolution optical technique, based on the multi-wavelength UV-visible-near IR extinction spectroscopy, was applied at the exhaust of an automotive diesel engine to investigate the post-injection strategy impact on the fuel vapor. Experimental investigations were carried out using three fuels: commercial diesel (B5), a blend of 80% diesel with 20% by vol. of gasoline (G20) and a blend of 80% diesel with 20% by vol. of n-butanol (BU20). Experiments were performed at the engine speed of 2500rpm and 0.8MPa of brake mean effective pressure exploring two post-injection timings and two EGR rates. The optical diagnostic allowed evaluating, during the post-injection activation, the evolution of the fuel vapor in the engine exhaust line. The investigation was focused on the impact of post-injection strategy and fuel properties on the aptitude to produce hydrocarbon rich gaseous exhaust for the regeneration of diesel particulate trap (DPF).
2015-04-14
Technical Paper
2015-01-0927
Luca Marchitto, Gerardo Valentino, Simona Merola, Cinzia Tornatore
Abstract The use of alcohols as alternative to gasoline for fuelling spark-ignition (SI) engines is widespread. Growing interest is paid for n-butanol because of its characteristics that are similar to gasoline. If compared with other alcohols, n-butanol has higher energy content and miscibility with gasoline, lower hygroscope and corrosive properties making it an attractive solution for gasoline replacement. Even if several studies have been conduced to characterize the n-butanol combustion within Spark Ignition engines, few data are available on atomization and spray behavior. This paper reports the results of an experimental investigation to characterize the velocity vector field of two fuel-sprays injected by a 6-hole nozzle for Direct Injection Spark Ignition (DISI) engine. 2D Mie-scattering and Particle Image Velocimetry (PIV) measurements were carried out in an optically accessible vessel at ambient temperature and pressure.
2015-04-14
Technical Paper
2015-01-0754
Simona Silvia Merola, Adrian Irimescu, Luca Marchitto, Cinzia Tornatore, Gerardo Valentino
Abstract Crank angle resolved imaging in the UV-visible spectral range was used to investigate flame front characteristics during normal combustion, surface ignition and light knock conditions. ‘Line of sight’ measurements provided information on local wrinkling: the evaluation was based on a statistical approach, with multiple frames taken at the same crank angle during consecutive cycles. This allowed the results during normal combustion to be representative for the specific operational conditions and to a good degree independent from the effects of cyclic variation. Abnormal combustion on the other hand, was investigated on a cycle-to-cycle basis, given the stochastic nature of such phenomena. The experimental trials were performed at fixed engine speed on an optically accessible direct injection spark ignition (DISI) engine equipped with the cylinder head of a four cylinder 16-valves commercial power unit.
2015-04-14
Journal Article
2015-01-0748
Simona Silvia Merola, Adrian Irimescu, Cinzia Tornatore, Luca Marchitto, Gerardo Valentino
Abstract In this study, experiments were carried out in an optical single-cylinder Direct Injection Spark Ignition engine fuelled with n-butanol and gasoline, alternatively. The engine is equipped with the head of a commercial turbocharged engine with similar geometrical specifications (bore, stroke, compression ratio). The head has four valves and a centrally located spark device with surface charge ignition. A conventional elongated hollow Bowditch piston is used and an optical crown, accommodating fused-silica window, is screwed onto it. The injector is side mounted and features 6 holes oriented to guide the jets towards the piston crown. During the experimental activity, the injection pressure was maintained at 100 bar for all conditions; the injection timing and the number of injections were adjusted to investigate their influence on combustion and emissions.
2010-04-12
Technical Paper
2010-01-0333
Gerardo Valentino, Stefano Iannuzzi, Felice E. Corcione
In this paper, a Low Temperature Premixed Combustion (LTPC) was investigated employing a four cylinder D.I. common rail Diesel engine, used for passenger cars on the European market. Experiments were carried out setting the engine speed at 2500 rpm with a fuel amount of 26 mg/str to realize an operating condition close to the point of NEDC at 0.8 MPa of BMEP. The experimental approach was the management of the start of injection, injection pressure and EGR rates as a method to control NOx and soot production. The investigation was first carried out testing engine performances and emissions as set from the commercial engine map. Afterward, engine tests were carried out exploring performances, gaseous and smoke emissions at late start of combustion [10 to 17.5 cad ATDC], injection pressures from 80 to 120 MPa and EGR rates up to 50%.
2014-10-13
Technical Paper
2014-01-2674
Gerardo Valentino, Stefano Iannuzzi
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.
2014-10-13
Technical Paper
2014-01-2743
Luca Marchitto, Simona Merola, Cinzia Tornatore, Gerardo Valentino
Abstract Alcohols are largely used in spark-ignition (SI) engines as alternative fuels to gasoline. Particularly, the use of butanol meets growing interest due to its properties that are similar to gasoline, if compared with other alcohols. This paper aims to make a comparative analysis on the atomization process of gasoline and n-butanol fuel injected by a multi-hole injector nozzle for spark ignition engines. Phase Doppler Anemometry technique was applied to investigate the behavior of a spray emerging from a six-hole nozzle for direct injection spark ignition engine applications. Commercial gasoline and pure n-butanol were investigated. The fuels were injected at two pressures: namely at 5 and 10 MPa, in a test vessel at quiescent air conditions, ambient temperature and backpressure. Droplets diameter and velocity were estimated along the axis and on the edge direction of a jet through Phase Doppler Anemometry in order to provide useful information on the atomization process.
2014-10-13
Technical Paper
2014-01-2765
Simona Silvia Merola, Cinzia Tornatore, Luca Marchitto, Gerardo Valentino, Adrian Irimescu
Abstract Liquids with stable suspensions of nanoscale materials are defined as nanofluids. As reported in recent scientific literature, a very small amount of suspended nanostructures has the potential to enhance the thermo physical, transport and radiative properties of the base fluid. One of the main applications of this technology is in the field of combustion and fuels. In fact, adding nanomaterials (such as metals, oxides, carbides, nitrides, or carbon-based nanostructures) to liquid fuels is able to enhance ignition and combustion. The focus of this research is to gain a fundamental understanding of the characteristics of a nanofluid fuel prepared using carbon nanoparticles (CNPs) and multi-walled carbon nanotubes (MWCNTs) dispersed in butanol. This study starts with the investigation of the optical properties of the mixtures. The transmission spectra of the nanofluids are measured in a wide wavelength range from UV (250 nm) to near IR (800 nm).
2013-04-08
Technical Paper
2013-01-0915
Gerardo Valentino, Stefano Iannuzzi, Felice Esposito Corcione
In the present paper, results of an experimental investigation carried out in a modern Diesel engine running at different operating conditions and fuelled with commercial diesel and n-butanol-diesel blend are reported. The investigation was focused on the management of injection strategy and combustion timing (CA50) exploring the effect of intake oxygen concentration and boost pressure on engine out emissions. The aim of the paper was to compare, with respect to commercial diesel, the effects of a fuel blend with a lower cetane number and higher volatility on performance and engine out emissions. Engine tests, with baseline diesel and a blend made by the baseline low sulphur diesel with 20% in volume of n-butanol (B20), were performed comparing engine out gaseous, smoke emissions and combustion efficiency. The investigation was performed on a turbocharged, water cooled, DI diesel engine, equipped with a common rail injection system.
2013-04-08
Technical Paper
2013-01-1318
Cinzia Tornatore, Simona Merola, Gerardo Valentino, Luca Marchitto
In-cylinder optical diagnostic was applied to study butanol-gasoline blend combustion in a SI engine. Spark timing and fuel injection mode were changed to work in normal and knocking conditions. The experiments were realized in a single-cylinder ported fuel injection SI engine with an external boosting device. The engine worked like-stoichiometric mixture at 2000 rpm, medium boosting and wide open throttle. UV-visible natural emission spectroscopy allowed to follow the formation and the evolution of the main compounds and radical species that characterize the combustion process from the spark ignition until the exhaust. Particular interest was devoted to OH and CO₂* evolution, and to the spectral evidence of soot precursors due to fuel deposits burning. OH resulted the best marker for combustion both in normal and abnormal conditions.
2013-04-08
Technical Paper
2013-01-1127
Simona Silvia Merola, Andrea De Filippo, Gerardo Valentino, Cinzia Tornatore, Luca Marchitto, Stefano Iannuzzi
Multi-wavelength ultraviolet-visible extinction spectroscopy was applied to follow the evolution of fuel vapor injected by post-injection along the exhaust line of a common-rail turbocharged direct-injection diesel engine at moderate speed and load. The exhaust line was specifically designed and customized to allow the insertion of the optical access upstream of the Diesel Oxidation Catalyst. During the experimental campaign, the engine was fuelled with commercial B5 fuel and a B30 v/v blend of RME and ultra low sulfur diesel, monitoring emissions upstream of the catalyst and exhaust gas temperature across the catalyst. Tests were performed at different engine operating conditions with particular attention to moderate speed and load.
2012-09-10
Technical Paper
2012-01-1723
Simona Silvia Merola, Cinzia Tornatore, Gerardo Valentino, Luca Marchitto
One promising approach to reduce pollutants from compression ignition engines is the Partially-Premixed- Combustion in which engine out emissions can be reduced by promoting mixing of fuel and air prior to auto-ignition. A great interest for a premixed combustion regime is the investigation on fuels with different reactivity by blending diesel with lower cetane number and higher volatility fuels. In fact, fuels more resistant to auto-ignition give longer ignition delay that may enhance the fuel/air mixing prior to combustion. During the ignition delay period, the fuel spray atomizes into small droplets, vaporizes and mixes with air. As the piston moves towards TDC, as soon as the mixture temperature reaches the ignition point, instantaneously some pre-mixed amount of fuel and air ignites. The balance of fuel that does not burn in premixed combustion is consumed in the rate-controlled combustion phase, also known as diffusion combustion.
2012-04-16
Technical Paper
2012-01-1127
Gerardo Valentino, Felice E. Corcione, Stefano Iannuzzi, Simone Serra
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.
1993-11-01
Technical Paper
931948
Felice E. Corcione, Annunziata Fusco, Gerardo Valentino, Francesco Papetti
The air fuel mixing process of a small direct injection (d.i.) diesel engine, equipped with two different re-entrant combustion chambers and two nozzles having unlike spray angles, has been studied by integrated use of in-cylinder laser Doppler velocimetry (LDV) measurements, engine tests, and KIVA simulations. The LDV measurements have been carried out in an engine with optical access motored at 2200 rpm. The engine tests have been performed on a similar engine at the same speed, at fixed start of combustion, and different air-fuel ratio. The KIVA-II simulations have been made using as initial conditions the parameters determined by LDV and engine tests. The re-entrant bowl with higher levels of air velocity and turbulent kinetic energy at the time of injection gives the best performance. The nozzle having a spray angle of 150° which injects the fuel into the regions at higher turbulent kinetic energy lowers the smoke emission levels.
1997-05-01
Technical Paper
971678
Gerardo Valentino, Felice E. Corcione, Giovanni Seccia
The present paper aims at developing a general method to estimate integral and microtime scales of turbulent in-cylinder flow field in reciprocating engines. The ensemble average technique was used to compute the integral time scale from the single point time autocorrelation function, whereas the microtime scale, representative of the most rapid changes that occur in the fluctuation, was computed as the intercept of the parabola that matches the autocorrelation function at the origin. Further, the microtime scale was also estimated by spectral analysis through the energy spectral density function of the ensemble turbulent fluctuation and the results obtained by the two methods were compared. The procedures were applied to the tangential component of the instantaneous velocity data collected, at different engine speeds (1,000, 1,500, 2,000 rpm), within a motored d.i. diesel engine equipped with a re-entrant combustion chamber, using the Laser Doppler Anemometry (LDA) technique.
1994-03-01
Technical Paper
940284
Felice E. Corcione, Gerardo Valentino
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.
1993-10-01
Technical Paper
932700
Gerardo Valentino, Duane Kaufman, Patrick Farrell
Intake valve flow patterns have been measured quantitatively using particle image velocimetry (PIV) for a commercial 4-valve diesel cylinder head and valve system. The measurements have been made for low (600 engine RPM) and higher (1000 engine RPM) speeds, and at several planes in the valve curtain area. The measurements involve double exposure photography of laser light scattered by seed particles (≅1 μm) from a laser light sheet (≅ 0.5 mm by 50 mm) through an imaging system onto silver halide film. Subsequent processing produces the local particle displacement between the two exposures. Combined with the known time interval between exposures, the displacement information can produce velocity vectors at many locations in the field of view. The results of the experiments are shown as vector plots for each operating condition. In the plane of the illuminating laser sheet, velocity vectors representing local gas velocity are produced.
2016-04-05
Technical Paper
2016-01-0738
Luca Marchitto, Simona Silvia Merola, Cinzia Tornatore, Gerardo Valentino
Abstract UV-visible digital imaging and 2D chemiluminescence were applied on a single cylinder optically accessible compression ignition engine to investigate the effect of different alcohol/diesel fuel blends on the combustion mechanism. The growing request for greenhouse gas emission reduction imposes to consider the use of alternative fuels with the aim of both partially replacing the diesel fuel and reducing the fossil fuel consumption. To this purpose, the use of ABE (Acetone-Butanol-Ethanol) fermentation could represent an effective solution. Even if the different properties of alcohols compared to Diesel fuel limit the maximum blend concentration, low blend volume fractions can be used for improving combustion efficiency and exhaust emissions. The main objective of this study was to investigate the effects of the different fuel properties on the combustion evolution within the combustion chamber of a prototype optically accessible compression ignition engine.
2015-09-06
Journal Article
2015-24-2520
Simona Silvia Merola, Adrian Irimescu, Gerardo Valentino, Cinzia Tornatore, Stefano Silva, Alberto Grimaldi, Eugenio Carugati
Abstract A plasma ignition system was tested in a GDI engine with the target of combustion efficiency improvement without modifying engine configuration. The plasma was generated by spark discharge and successively sustained to enhance its duration up to 4 ms. The innovative ignition system was tested in an optically accessible single-cylinder DISI engine to investigate the effects of plasma on kernel stability and flame front propagation under low loads and lean mixture (λ≅1.3). The engine was equipped with the head of a commercial turbocharged engine with similar geometrical specifications (bore, stroke, compression ratio). All experiments were performed at 2000 rpm and 100 bar injection pressure. UV-visible 2D chemiluminescence was applied in order to study the flame front inception and propagation with particular interest in the early combustion stages. A bandpass filter allowed selecting luminous signal due to OH radicals.
2016-10-17
Journal Article
2016-01-2230
Vincenzo De Bellis, Fabio Bozza, Daniela Siano, Gerardo Valentino
Abstract In this paper, the results of an extensive experimental analysis regarding a twin-cylinder spark-ignition turbocharged engine are employed to build up an advanced 1D model, which includes the effects of cycle-by-cycle variations (CCVs) on the combustion process. Objective of the activity is to numerically estimate the CCV impact primarily on fuel consumption and knock behavior. To this aim, the engine is experimentally characterized in terms of average performance parameters and CCVs at high and low load operation. In particular, both a spark advance and an air-to-fuel ratio (α) sweep are actuated. Acquired pressure signals are processed to estimate the rate of heat release and the main combustion events. Moreover, the Coefficient of Variation of IMEP (CoVIMEP) and of in-cylinder peak pressure (CoVpmax) are evaluated to quantify the cyclic dispersion and identify its dependency on peak pressure position.
2016-10-17
Technical Paper
2016-01-2178
Daniela Siano, Gerardo Valentino, Fabio Bozza, Arturo Iacobacci, Luca Marchitto
Abstract In this paper, a downsized twin-cylinder turbocharged spark-ignition engine is experimentally investigated at test-bench in order to verify the potential to estimate the peak pressure value and the related crank angle position, based on vibrational data acquired by an accelerometer sensor. Purpose of the activity is to provide the ECU of additional information to establish a closed-loop control of the spark timing, on a cycle-by-cycle basis. In this way, an optimal combustion phasing can be more properly accomplished in each engine operating condition. Engine behavior is firstly characterized in terms of average thermodynamic and performance parameters and cycle-by-cycle variations (CCVs) at high-load operation. In particular, both a spark advance and an A/F ratio sweep are actuated. In-cylinder pressure data are acquired by pressure sensors flush-mounted within the combustion chamber of both cylinders.
2016-04-05
Technical Paper
2016-01-0710
Adrian Irimescu, Simona Silvia Merola, Cinzia Tornatore, Gerardo Valentino, Alberto Grimaldi, Eugenio Carugati, Stefano Silva
Abstract Considering the generalized diversification of the energy mix, the use of alcohols as gasoline replacement is proposed as a viable option. Also, alternative control strategies for spark ignition engines (SI) such as lean operation and exhaust gas recirculation (EGR) are used on an ever wider scale for improving fuel economy and reducing the environmental impact of automotive engines. In order to increase the stability of these operating points, alternative ignition systems are currently investigated. Within this context, the present work deals about the use of plasma assisted ignition (PAI) in a direct injection (DI) SI engine under lean conditions and cooled EGR, with gasoline and n-butanol fueling. The PAI system was tested in an optically accessible single-cylinder DISI engine equipped with the head of a commercial turbocharged power unit with similar geometrical specifications (bore, stroke, compression ratio).
2016-04-05
Journal Article
2016-01-0601
Sebastiano Breda, Alessandro D'Adamo, Stefano Fontanesi, Nicola Giovannoni, Francesco Testa, Adrian Irimescu, Simona Merola, Cinzia Tornatore, Gerardo Valentino
Abstract The occurrence of knock is the most limiting hindrance for modern Spark-Ignition (SI) engines. In order to understand its origin and move the operating condition as close as possible to onset of this potentially harmful phenomenon, a joint experimental and numerical investigation is the most recommended approach. A preliminary experimental activity was carried out at IM-CNR on a 0.4 liter GDI unit, equipped with a flat transparent piston. The analysis of flame front morphology allowed to correlate high levels of flame front wrinkling and negative curvature to knock prone operating conditions, such as increased spark timings or high levels of exhaust back-pressure. In this study a detailed CFD analysis is carried out for the same engine and operating point as the experiments. The aim of this activity is to deeper investigate the reasons behind the main outcomes of the experimental campaign.
2013-10-14
Journal Article
2013-01-2638
Simona Silvia Merola, Luca Marchitto, Cinzia Tornatore, Gerardo Valentino, Adrian Irimescu
Detailed experimental information on the early stages of spark ignition process represent a substantial part for guiding the development of engines with higher efficiencies and reduced pollutant emissions. Flame kernel formation influences strongly combustion development inside the cylinder, especially for a direct injection spark ignition engine. This study presents the analysis of the evolution of spark-ignited flame kernels with detailed view upon cycle-to-cycle variations. Experiments are performed in a SI optical engine equipped with the cylinder head and injection system of a commercial turbocharged engine. Blend of commercial gasoline and butanol (40% by volume) is tested at stoichiometric and lean mixture conditions. Experiments are carried out at 2000 rpm through conventional tests (based on in-cylinder pressure measurements and exhaust emission analysis) and through optical diagnostics. In particular, UV-visible digital imaging and natural emission spectroscopy are applied.
2011-06-09
Journal Article
2011-37-0003
Simona Silvia Merola, Luca Marchitto, Felice Corcione, Gerardo Valentino, Cinzia Tornatore
To meet the future stringent emission standards, innovative diesel engine technology, exhaust gas after-treatment, and clean alternative fuels are required. Oxygenated fuels have showed a tendency to decrease internal combustion engine emissions. In the same time, advanced fuel injection modes can promote a further reduction of the pollutants at the exhaust without penalty for the combustion efficiency. One of the more interesting solutions is provided by the premixed low temperature combustion (LTC) mechanism jointly to lower-cetane, higher-volatility fuels. In this paper, to understand the role played by these factors on soot formation, cycle resolved visualization, UV-visible optical imaging and visible chemiluminescence were applied in an optically accessed high swirl multi-jets compression ignition engine. Combustion tests were carried out using three fuels: commercial diesel, a blend of 80% diesel with 20% gasoline (G20) and a blend of 80% diesel with 20% n-butanol (BU20).
2011-09-11
Technical Paper
2011-24-0057
Simona Silvia Merola, Cinzia Tornatore, Gerardo Valentino, Luca Marchitto, Felice Corcione
The addition of alcohol to conventional hydrocarbon fuels for a spark-ignition engine can increase the fuel octane rating and the power for a given engine displacement and compression ratio. In this work, the influence of butanol addition to gasoline was investigated. The experiments were performed in an optical ported fuel injection single-cylinder SI engine with an external boosting device. The engine was equipped with the head of a commercial SI turbocharged engine having the same geometrical specifications (bore, stroke and compression ratio). The effect of a blend of 20% of n-butanol and 80% of gasoline (BU20) on in-cylinder combustion process was investigated by cycle-resolved visualization. The engine worked at low speed, medium boosting and wide open throttle. Changes in spark timing and fuel injection phasing were considered. Comparisons between the flame luminosity and the combustion pressure data were performed.
2011-09-11
Technical Paper
2011-24-0045
Felice Corcione, Gerardo Valentino, Cinzia Tornatore, Simona Merola, Luca Marchitto
Optical imaging and UV-visible detection of in-cylinder combustion phenomena were made in a single cylinder optically accessed high swirl multi-jets compression ignition engine operating with two different fuels and two EGR levels. A commercial diesel fuel and a lighter fuel blend of diesel (80%) and gasoline (20%), named G20, were tested for two injection pressures (70 and 140 MPa) and injection timings in the range 11 CAD BTDC to 5 CAD ATDC. The blend G20 has a lower cetane number, is more volatile and more resistant to the auto-ignition than diesel yielding an effect on the ignition delay and on the combustion performance. Instantaneous fuel injection rate, in-cylinder combustion pressure, NOx and smoke engine out emissions were measured. Taking into account the particular configuration of the engine, the efficiency was estimated by determining the area under the working engine cycle.
2011-09-11
Technical Paper
2011-24-0049
Gerardo Valentino, Felice Corcione, Stefano Iannuzzi, Simone Serra
This paper reports results of an experimental investigation to demonstrate the potential to employ blends of fuels having low cetane numbers that can provide high resistance to auto-ignition to reduce simultaneously NOx and smoke. Because of the higher resistance to auto-ignition, blends of diesel and gasoline at different volume fraction may provide more time for the mixture preparation by increasing the ignition delay. The result produces the potential to operate under partially premixed low temperature combustion with lower levels of EGR without excessive penalties on fuel efficiency. In addition to the diesel fuel, the tested blends were mixed by the baseline diesel with 20% and 40% of commercial EURO IV 98 octane gasoline by volume, denoted G20 and G40. The experimental activity has been performed on a turbocharged, water cooled, DI diesel engine, equipped with a common rail injection system.
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