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Viewing 1 to 30 of 33968
2017-09-16
Journal Article
2017-01-9181
Zhongming Xu, Nengfa Tao, Minglei Du, Tao Liang, Xiaojun Xia
Abstract A coupled magnetic-thermal model is established to study the reason for the damage of the starter motor, which belongs to the idling start-stop system of a city bus. A finite element model of the real starter motor is built, and the internal magnetic flux density nephogram and magnetic line distribution chart of the motor are attained by simulation. Then a model in module Transient Thermal of ANSYS is established to calculate the stator and rotor loss, the winding loss and the mechanical loss. Three kinds of losses are coupled to the thermal field as heat sources in two different conditions. The thermal field and the components’ temperature distribution in the starting process are obtained, which are finally compared with the already-burned motor of the city bus in reality to predict the damage. The analysis method proposed is verified to be accurate and reliable through comparing the actual structure with the simulation results.
2017-09-04
Technical Paper
2017-24-0060
Nicolo Cavina, Nahuel Rojo, Lorella Ceschini, Eleonora Balducci, Luca Poggio, Lucio Calogero, Ruggero Cevolani
The recent search for extremely efficient spark-ignition engines has implied a great increase of in-cylinder pressure and temperature levels, and knocking combustion mode has become one of the most relevant limiting factors. This paper reports the main results of a specific project carried out as part of a wider research activity, aimed at modelling and real-time controlling knock-induced damage on aluminium forged pistons. The paper shows how the main damage mechanisms (erosion, plastic deformation, surface roughness, hardness reduction) have been identified and isolated, and how the corresponding symptoms may be measured and quantified. The second part of the work then concentrates on understanding how knocking combustion characteristics affect the level of damage done, and which parameters are mainly responsible for piston failure.
2017-09-04
Technical Paper
2017-24-0059
Massimo FERRERA
The 2020+ CO2 and noxious emission limits will impose drastic technological choices. Even though in 2030 65% of road transportation vehicles will be still powered by an Internal Combustion Engine, a progressive increase of hybrids and battery electric vehicles will be confirmed. In parallel, the use of Low-Carbon Alternative Fuels, such as Natural Gas/Biomethane, will play a fundamental role in accelerating the process of de-carbonisation of the transportation sector supporting the virtuous Circular Economy. Since the nineties FCA invested in Compressed Natural Gas (CNG) powered vehicles becoming Market leader with one of the largest related product portfolios in Europe. A progressive improvement of this technology has been always pursued but, facing the next decades, a further improvement of the current CNG powertrain technology is mandatory to achieve even higher efficiency and remove residual gaps versus conventional fuels.
2017-09-04
Technical Paper
2017-24-0057
Roberto Finesso, Omar Marello, Ezio Spessa, Yixin Yang, Gilles Hardy
A model-based control of BMEP (Brake Mean Effective Pressure) and NOx emissions has been developed and assessed for a Euro VI 3.0L diesel engine for heavy-duty applications. The control is based on a zero-dimensional real-time combustion model, which is capable of simulating the HRR (heat release rate), in-cylinder pressure, brake torque, exhaust gas temperatures, NOx and soot engine-out levels. The real-time combustion model has been realized by integrating and improving previously developed simulation tools. The chemical energy release has been simulated using the accumulated fuel mass approach. The in-cylinder pressure was estimated on the basis of a single-zone heat release model, using the net energy release as input. The latter quantity was obtained starting from the simulated chemical energy release, and evaluating the heat transfer of the charge with the walls.
2017-09-04
Technical Paper
2017-24-0065
Dr. Helmut Ruhland, Thomas Lorenz, Jens Dunstheimer, Albert Breuer, Maziar Khosravi
An integral part of combustion system development for previous NA gasoline engines was the optimization of charge motion towards the best compromise in terms of full load performance, part load stability, emissions and, last but not least, fuel economy. This situation might have changed with the introduction of GTDI engines. While it is generally accepted that an increased charge motion level improves the mixture preparation of a direct injection gasoline engine, the tradeoff in terms of performance seems to become less dominant as the boosting systems of modern engines are typically sound enough to compensate the flow losses generated by the more restrictive ports. Certainly the increased boost level does not come for free. Increased charge motion generates higher pumping- and wall heat losses. Hence it is questionable and engine dependent, whether more charge motion is always better.
2017-09-04
Technical Paper
2017-24-0066
Maria Cristina Cameretti, Roberta De Robbio, Raffaele Tuccillo
The present study deals with the simulation of a Diesel engine fuelled by natural gas/diesel in dual fuel mode to optimize the engine behaviour in terms of performance and emissions. In dual fuel mode, the natural gas is introduced into the engine’s intake system. Near the end of the compression stroke, diesel fuel is injected and ignites, causing the natural gas to burn. The engine itself is virtually unaltered, but for the addition of a gas injection system. The CO2 emissions are considerably reduced because of the lower carbon content of the fuel. Furthermore, potential advantages of dual-fuel engines include diesel-like efficiency and brake mean effective pressure with much lower emissions of oxides of nitrogen and particulate matter. In previous papers [1, 2, 3], the authors have presented some CFD results obtained by the KIVA 3V and Fluent codes by varying the diesel/NG ratio and the diesel pilot injection timing at different loads.
2017-09-04
Technical Paper
2017-24-0043
Thomas Kammermann, Jann Koch, Yuri M. Wright, Patrik Soltic, Konstantinos Boulouchos
The interaction of turbulent premixed methane combustion with the surrounding flow field can be studied using optically accessible test rigs such as a rapid compression expansion machine (RCEM). The high flexibility offered by such a machine allows its operation at various thermochemical conditions at ignition. However, limitations inherent to such test rigs due to the absence of an intake stroke do not allow turbulence production as found in IC-engines. Hence, means to introduce turbulence have to be implemented and the relevant turbulence quantities have to be identified in order to enable comparability with engine relevant conditions. A dedicated high-pressure direct injection of air at the beginning of the compression phase is considered as a measure to generate adjustable turbulence intensities at ignition timing and during the early flame propagation.
2017-09-04
Technical Paper
2017-24-0044
Jeremy Rochussen, Jeff Son, Jeff Yeo, Mahdiar Khosravi, Patrick Kirchen, Gordon McTaggart-Cowan
Alternative fuel injection systems and advanced in-cylinder diagnostics are two important tools for engine development; however, the rapid and simultaneous achievement of these goals is often limited by the space available in the cylinder head. Here, a research-oriented cylinder head is developed for use on a single cylinder 2-litre engine, and permits three simultaneous in-cylinder combustion diagnostic tools (cylinder pressure measurement, infrared (IR) absorption, and multi-color pyrometry). In addition, a modular injector mounting system enables the use of a variety of direct fuel injectors for both gaseous and liquid fuels. The design of the all-new cylinder head was derived from a production cylinder head, which was sectioned and laser scanned to create a parametric model.
2017-09-04
Technical Paper
2017-24-0045
Blane Scott, Christopher Willman, Ben Williams, Paul Ewart, Richard Stone, David Richardson
In-cylinder temperature measurements are vital for the validation of gasoline engine modelling and useful in their own right for explaining differences in engine performance. The underlying chemical reactions in combustion are highly sensitive to temperature and affect emissions of both NOx and particulate matter. The two techniques described here are complementary, and can be used for insights into the quality of mixture preparation and comparing the in-cylinder temperatures of port fuel injection (PFI) compared with gasoline direct injection (GDI), so as to explain the differences in volumetric efficiency. The influence of fuel composition on in-cylinder mixture temperatures can also be resolved. Laser Induced Grating Spectroscopy (LIGS) provides point temperature measurements with a pressure dependent precision in the range 0.1 to 1.0%; as the pressure increases the precision improves. This allows resolution of temperature differences between PFI and GDI mixture preparation.
2017-09-04
Technical Paper
2017-24-0046
Richard Stone, Ben Williams, Paul Ewart
The increased efficiency and specific output with Gasoline Direct Injection (GDI) engines are well known, but so too are the higher levels of Particulate Matter emissions compared with Port Fuel Injection (PFI) engines. To minimise Particulate Matter emissions, then it is necessary to understand and control the mixture preparation process, and important insights into GDI engine combustion can be obtained from optical access engines. Such data is crucial for validating models that predict flows, sprays and air fuel ratio distributions. Mie scattering can be used for semi-quantitative measurements of the fuel spray and this can be followed with Planar Laser Induced Fluorescence (PLIF) for determining the air fuel ratio and temperature distributions. With PLIF, very careful in-situ calibration is needed, and for temperature this can be provided by Laser Induced Thermal Grating Spectroscopy (LITGS).
2017-09-04
Technical Paper
2017-24-0039
Daniele Piazzullo, Michela Costa, Youngchul Ra, Vittorio ROCCO, Ankith Ullal
Bio-derived fuels are drawing more and more attention in the internal combustion engine (ICE) research field in recent years. Those interests in use of renewable biofuels in ICE applications derive from energy security issues and, more importantly, from environment pollutant emissions concerns. High fidelity numerical study of engine combustion requires advanced computational fluid dynamics (CFD) to be coupled with detailed chemical kinetic models. This task becomes extremely challenging if real fuels are taken into account, as they include a mixture of hundreds of different hydrocarbons, which prohibitively increases computational cost. Therefore, along with employing surrogate fuel models, reduction of detailed kinetic models for multidimensional engine applications is preferred. In the present work, a reduced mechanism was developed for primary reference fuel (PRF) using the directed relation graph (DRG) approach. The mechanism was generated from an existing detailed mechanism.
2017-09-04
Technical Paper
2017-24-0040
Insuk Ko, Kyoungdoug Min, Federico Rulli, Alessandro D'Adamo, Fabio Berni, Stefano Fontanesi
The increasing interest in the application of Large Eddy Simulation (LES) to Internal Combustion Engines (hereafter ICEs) flows is motivated by its capability to capture spatial and temporal evolution of turbulent flow structures. Furthermore, LES is universally recognized as capable of simulating highly unsteady and random phenomena driving cycle-to-cycle variability (CCV) and cycle-resolved events such as knock and misfire. Several quality criteria were proposed in the recent past to estimate LES uncertainty: however, definitive conclusions on LES quality criteria for ICEs are still far to be found. This paper focuses on the application of LES quality criteria to the TCC-III single-cylinder optical engine from University of Michigan and GM Global R&D; the analyses are carried out under motored condition.
2017-09-04
Technical Paper
2017-24-0041
Daniele Piazzullo, Michela Costa, Luigi Allocca, Alessandro Montanaro, Vittorio ROCCO
In gasoline direct injection (GDI) engines, dynamics of the possible spray-wall interaction are key factors affecting the air-fuel mixture distribution and equivalence ratio at spark timing, hence influencing the development of combustion and the pollutants formation at the exhaust. Gasoline droplets impact may rebound with consequent secondary atomization or deposit in the liquid phase over walls as a wallfilm. This last slowly evaporate with respect to free droplets, leading to local enrichment of the mixture, hence to increased unburned hydrocarbons and particulate matter emissions. In this scenario, complex phenomena characterize the turbulent multi-phase system where heat transfer involves the gaseous mixture (made of air and gasoline vapour), the liquid phase (droplets not yet evaporated and wallfilm) and the solid wall, especially in the so-called wall-guided mixture formation mode.
2017-09-04
Technical Paper
2017-24-0042
Ali Jannoun, Xavier Tauzia, Pascal Chesse, Alain Maiboom
Residual gas plays a crucial role in the combustion process of spark ignited engines. It acts as a diluent and has a huge impact on pollutant emissions (NOx and CO emissions), engine efficiency and tendency to knock. Therefore, characterizing the residual gas fraction is an essential task for engine modelling and calibration purposes. Thus, an in-cylinder sampling technique was developed on a spark ignited VVT engine to measure residual gas fraction during the compression phase. Two gas sampling valves were flush mounted to the combustion chamber walls; they are located between the intake valves and between intake and exhaust valves respectively. Sampled gas was stocked in a sampling bag using a vacuum pump and measured with a standard gas analyzer. This paper describes in details the sampling technique and proposes a methodology allowing the evaluation of the residual gas fraction. For this purpose, five kinds of tests were undertaken.
2017-09-04
Technical Paper
2017-24-0052
Nicolo Cavina, Nahuel Rojo, Andrea Businaro, Alessandro Brusa, Enrico Corti, Matteo De Cesare
The paper presents simulation and experimental results of the effects of intake water injection on the main combustion parameters of a turbo-charged, direct injection spark ignition engine. Water injection is more and more considered as a viable technology to further increase specific output power of modern spark ignition engines, enabling extreme downsizing concepts and the associated efficiency increase benefits. The paper initially presents the main results of a one-dimensional simulation analysis carried out to highlight the key parameters (injection position and phasing, water-to-fuel ratio, water temperature and pressure) and their effects on combustion (in-cylinder and exhaust temperature reduction, knock tendency suppression, …).
2017-09-04
Technical Paper
2017-24-0053
Silvio A. Pinamonti, Domenico Brancale, Gerhard Meister, Pablo Mendoza
The use of state of the art simulation tools to allow for effective front-loading of the calibration process is essential to off-set these additional efforts; therefore, the process needs a critical model validation where the correlation in dynamic conditions is used as a preliminary insight of representation domain of a mean value engine model. This paper focuses on the methodologies for correlating dynamic simulations with vehicle measured dynamic data (fundamental engine parameters and gaseous emissions) obtained using dedicated instrumentation on a diesel vehicle. This correlation is performed using simulated tests run within the AVL mean value model MoBEO (model based engine optimization).
2017-09-04
Technical Paper
2017-24-0054
Francesco de Nola, Giovanni Giardiello, Alfredo Gimelli, Andrea Molteni, Massimiliano Muccillo, Roberto Picariello
In the last few years, the automotive industry had to face three main challenges: the compliance of more severe pollutant emission limits, better engine performance in terms of torque and drivability and the simultaneous demand for a significant reduction in fuel consumption as well. These conflicting goals have driven the evolution of automotive engines. In particular, the achievement of all these mandatory aims, together with the increasingly stringent requirements for carbon dioxide reduction, led to the development of highly complex engine architectures needed to perform advanced operating strategies. Thus, Variable Valve Actuation (VVA), Exhaust Gas Recirculation (EGR), Gasoline Direct Injection (GDI), turbocharging, powertrain hybridization and other solutions have gradually and widely equipped the modern internal combustion engines, enhancing the possibilities to achieve the required goals.
2017-09-04
Technical Paper
2017-24-0055
Enrico Corti, Claudio Forte, Gian Marco Bianchi, Lorenzo Zoffoli
The performance optimization of modern Spark Ignition engines is limited by knock occurrence: heavily downsized engines often are forced to work in the Knock-Limited Spark Advance (KLSA) range. Knock control systems monitor the combustion process, allowing to achieve a proper compromise between performance and reliability. Combustion monitoring is usually carried out by means of accelerometers or ion sensing systems, but recently the use of cylinder pressure sensors is also becoming established, especially for motorsport applications. The cylinder pressure signal is often available in a calibration environment, where SA feedback control is used to avoid damages to the engine during automatic calibration.
2017-09-04
Technical Paper
2017-24-0049
Matteo De Cesare, Federico Covassin, Enrico Brugnoni, Luigi Paiano
The new driving cycles require a greater focus on wider engine operative area and especially in transient conditions where a proper air path control is a challenging task for emission and drivability. In order to achieve this goal, turbocharger speed measurement can give several benefits in boost pressure transient and over-speed prevention, letting the adoption of a smaller turbocharger, that can reduce further the turbo-lag enabling engine downspeeding. Until now, the use of a turbocharger speed sensor was considered expensive and rarely available for passenger cars, while it is used on high performance engines with the aim of maximizing the engine power and torque, mainly in steady state, eroding the safe-margin for turbocharger over-speed. Thanks to the availability of a new cost effective turbocharger speed technology, based on acoustic sensing, the turbocharger speed can be used also for passenger car applications.
2017-09-04
Technical Paper
2017-24-0048
Jose V. Pastor, Jose M. Garcia-Oliver, Antonio Garcia, Mattia Pinotti
In the past few years various studies have shown how the application of a highly premixed dual fuel combustion for CI engines leads a strong reduction for both pollutant emissions and fuel consumption. In particular a drastic soot and NOx reduction were achieved. In spite of the most common strategy for dual fueling has been represented by using two different injection systems, various authors are considering the advantages of using a single injection system to directly inject blends in the chamber. In this scenario, a characterization of the behavior of such dual-fuel blend spray became necessary, both in terms of inert and reactive ambient conditions. In this work, a light extinction imaging (LEI) has been performed in order to obtain two-dimensional soot distribution information within a spray flame of different diesel/gasoline commercial fuel blends. All the measurements were conducted in an optically accessible two-stroke engine equipped with a single-hole injector.
2017-09-04
Technical Paper
2017-24-0050
Anjan Rao Puttige, Robin Hamberg, Paul Linschoten, Goutham Reddy, Andreas Cronhjort, Ola Stenlaas
Improving turbocharger performance to increase engine efficiency has the potential to help meet current and upcoming exhaust legislation. One limiting factor is compressor surge, an air flow instability phenomenon capable of causing severe vibration and noise. To avoid surge, the turbocharger is operated with a safety margin (surge margin) which, as well as avoiding surge in steady state operation, unfortunately also lowers engine performance. This paper investigates the possibility of detecting compressor surge with a conventional engine knock sensor. It further recommends a surge detection algorithm based on their signals during transient engine operation. Three knock sensors were mounted on the turbocharger and placed along the axes of three dimensions of movement. The engine was operated in load steps starting from steady state. The steady state points of operation covered the vital parts of the engine speed and load range.
2017-09-04
Technical Paper
2017-24-0027
Nearchos Stylianidis, Ulugbek Azimov, Nobuyuki Kawahara, Eiji Tomita
A chemical kinetics and computational fluid-dynamics (CFD) analysis were performed to evaluate the combustion of syngas derived from biomass and coke-oven solid feedstock in a micro-pilot ignited supercharged dual-fuel engine under lean conditions. For this analysis, a new reduced syngas chemical kinetics mechanism was constructed and validated by comparing the ignition delay and laminar flame speed data with those obtained from experiments and other detail chemical kinetics analysis available in the literature. The reaction sensitivity analysis was conducted for ignition delay at elevated pressures in order to identify important chemical reactions that govern the combustion process. We found that HO2+OH=H2O+O2 and H2O2+H=H2+HO2 reactions showed very high sensitivity during high-pressure ignition delay times and had considerable uncertainty.
2017-09-04
Technical Paper
2017-24-0026
Davide Paredi, Tommaso Lucchini, Gianluca D'Errico, Angelo Onorati, Stefano Golini, Nicola Rapetto
The scope of the work presented in this paper was to apply the latest open source CFD achievements to design a state of art, direct-injection (DI), heavy-duty, natural gas-fueled engine. Within this context, an initial steady-state analysis of the in-cylinder flow was performed by simulating three different intake ducts geometries, each one with seven different valve lift values, chosen according to an estabilished methodology proposed by AVL. The discharge coefficient (Cd) and the Tumble Ratio (TR) were calculated in each case, and an optimal intake ports geometry configuration was assessed in terms of a compromise between the desired intensity of tumble in the chamber and the satisfaction of an adequate value of Cd. Subsequently, full-cycle, cold-flow simulations were performed for three different engine operating points, in order to evaluate the in-cylinder development of TR and turbulent kinetic energy (TKE) under transient conditions.
2017-09-04
Technical Paper
2017-24-0029
Tommaso Lucchini, Gianluca D'Errico, Tarcisio Cerri, Angelo Onorati, Gilles Hardy
Heavy-duty engines have to be carefully designed and optimized in a wide portion of their operating map to satisfy the emissions and fuel consumptions requirements for the different applications they are used for. Within this context, computational fluid dynamics is a useful tool to support combustion system design, making possible to test effects of injection strategies and combustion chamber design. Within this context, the predictive capability of the combustion model play a big role since it has to ensure accurate predictions in terms of cylinder pressure trace and the main pollutant emissions in a reduced amount of time. For this reason, both detailed chemistry and turbulence chemistry interaction need to be included. In this work, the authors intend to apply combustion models based on tabulated kinetics for the prediction of Diesel combustion in Heavy Duty Engines. Three different approaches were considered: well-mixed model, presumed PDF and flamelet progress variable.
2017-09-04
Technical Paper
2017-24-0028
Adèle Poubeau, Stephane Jay, Anthony Robert, Edouard Nicoud, Christian Angelberger
A speed transient performed in a four-valve single cylinder optical gasoline engine under motored conditions is investigated by means of an experimental campaign and Large-Eddy Simulations. Thorough analysis of the flow phenomena is performed, including characterization of kinetic energy, tumble ratios and velocity fields. Comparison between experimental and numerical results shows that high-fidelity simulations are able to capture well the main features of the flow, validating the use of LES for this type of engine configuration.
2017-09-04
Technical Paper
2017-24-0023
Karim Gharaibeh, Aaron W. Costall
Internal combustion engines are routinely developed using 1D engine simulation tools. A well-known limitation is the accuracy of the turbocharger compressor and turbine sub-models, which generally rely on hot gas bench-measured maps to characterize their performance. Such discrete map data is inherently too sparse to be used directly in simulation, and so a pre-processing algorithm interpolates and extrapolates the data to generate a wider and more densely populated map. Methods used for compressor map interpolation vary. They may be mathematical or physical in nature, but there is no unified approach, except for the fact that they often operate on input map data in SAE standard format. Indeed, for decades it has been common practice for turbocharger suppliers to share performance data with their engine OEM customers in this form.
2017-09-04
Technical Paper
2017-24-0022
Alessio Dulbecco, Gregory Font
Diesel engine pollutant emissions legislation is becoming more and more stringent. New driving cycles, including increasingly more severe transient engine operating conditions and low temperature ambient conditions, extend considerably the engine operating domain to be optimized to attain the expected engine performance. Technological innovations, such as high pressure injection systems, EGR loops and intake pressure boosting systems allow significant improvement of engine performance. Nevertheless, because of the high number of calibration parameters, combustion optimization becomes expensive in terms of resources. System simulation is a promising tool to perform virtual experiments and consequently to reduce costs, but for this models must be able to account for relevant in-cylinder physics to be sensitive to the impact of technology on combustion and pollutant formation.
2017-09-04
Technical Paper
2017-24-0025
Francesco Sapio, Andrea Piano, Federico Millo, Francesco Concetto Pesce
Development trends in modern Common Rail Fuel Injection System (FIS) show dramatically increasing capabilities in terms of optimization of the fuel injection pattern through a constantly increasing number of injection events per engine cycle along with a modulation and shaping of the injection rate. In order to fully exploit the potential of the abovementioned fuel injection pattern optimization, numerical simulation can play a fundamental role by allowing the creation of a kind of a virtual injection rate generator for the assessment of the corresponding engine outputs in terms of combustion characteristics such as burn rate, emission formation and combustion noise (CN). This paper is focused on the analysis of the effects of digitalization of pilot events in the injection pattern on Brake Specific Fuel Consumption (BSFC), CN and emissions for a EURO 6 passenger car 4-cylinder diesel engine.
2017-09-04
Technical Paper
2017-24-0024
Andrea Piano, Federico Millo, Davide Di Nunno, Alessandro Gallone
The need for achieving a fast warm up of the exhaust system has raised in the recent years a growing interest in the adoption of Variable Valve Actuation (VVA) technology for automotive diesel engines. As a matter of fact, different measures can be adopted through VVA to accelerate the warm-up of the exhaust system, such as using hot internal Exhaust Gas Recirculation (iEGR) to heat the intake charge, especially at part load, or adopting early Exhaust Valve Opening (eEVO) timing during the expansion stroke, so to increase the exhaust gas temperature during blowdown. In this paper a simulation study is presented evaluating the impact of VVA on the exhaust temperature of a modern light duty 4-cylinder diesel engine, 1.6 liters, equipped with a Variable Geometry Turbine (VGT).
2017-09-04
Technical Paper
2017-24-0035
Giulio Cazzoli, Claudio Forte, Gian Marco Bianchi, Stefania Falfari, Sergio Negro
The laminar burning speed is an important intrinsic property of a air-fuel mixture determining key combustion characteristics such as ignition delay and flame propagation, turbulent flame propagation and knock tendency. The laminar burning speed is a function of the fuel, equivalent ratio and mass fraction of the residual gases in the fresh mixture (EGR). It also depend on the unburned mixture temperature and pressure. Due to experimental limitations the laminar flame speeds over the full range of pressures and temperatures of an internal combustion engine, temperature can be as high as 1000 K and the pressure up to 35 bar with different value of EGR, are not available. The most widespread models used to extrapolate the experimental data to the engine conditions are derived from the model of Metghalchi and Keck. This family of models usually fail to correctly predict value really outside of the experimental space.
Viewing 1 to 30 of 33968