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Viewing 1 to 30 of 20246
2018-01-16
Event
2017-09-19
Event
2017-09-16
Journal Article
2017-01-9180
Johannes Wurm, Eetu Hurtig, Esa Väisänen, Joonas Mähönen, Christoph Hochenauer
Abstract The presented paper focuses on the computation of heat transfer related to continuously variable transmissions (CVTs). High temperatures are critical for the highly loaded rubber belts and reduce their lifetime significantly. Hence, a sufficient cooling system is inevitable. A numerical tool which is capable of predicting surface heat transfer and maximum temperatures is of high importance for concept design studies. Computational Fluid Dynamics (CFD) is a suitable method to carry out this task. In this work, a time efficient and accurate simulation strategy is developed to model the complexity of a CVT. The validity of the technique used is underlined by field measurements. Tests have been carried out on a snowmobile CVT, where component temperatures, air temperatures in the CVT vicinity and engine data have been monitored. A corresponding CAD model has been created and the boundary conditions were set according to the testing conditions.
2017-09-04
Technical Paper
2017-24-0173
Jean-Charles Dabadie, Antonio Sciarretta, Gregory Font, Fabrice Le Berr
Due to more and more complex powertrain architectures and the necessity to optimize them on the whole driving conditions, simulation tools are becoming indisputable for car manufacturers and suppliers. Indeed, simulation is at the basis of any algorithm aimed at finding the best compromise between fuel consumption, emissions, drivability, and performance during the conception phase. For hybrid vehicles, the energy management strategy is a key driver to ensure the best fuel consumption and thus has to be optimized carefully as well. In this regard, the coupling of an offline hybrid strategy optimizer (HOT) based on Pontryagin’s minimum principle (PMP) and an online equivalent-consumption-minimization strategy (ECMS) generator is presented. Additionally, methods to estimate the efficiency maps and other overall characteristics of the main powertrain components (thermal engine, electric motor(s), and battery) from a few design parameters are shown.
2017-09-04
Technical Paper
2017-24-0167
Enrico Mattarelli, Carlo Rinaldini, Tommaso Savioli, Giuseppe Cantore, Alok Warey, Michael Potter, Venkatesh Gopalakrishnan, Sandro Balestrino
A CFD study on a 2-stroke (2-S) opposed piston high speed direct injection (HSDI) Diesel engine is reported in this work. The engine main features (bore, stroke, port timings, et cetera) were defined in a previous stage of the project, with the support of CFD-1D engine simulations and empirical hypotheses. The current analysis is focused on the assembly made up of scavenge ports, manifold and cylinder. The first step of the study consisted in the construction of a parametric mesh on a simplified geometry. Two geometric parameters and 3 different operating conditions were considered. A CFD-3D simulation by using a customized version of the KIVA-4 code was performed on a set of 243 different cases, sweeping all the most interesting combinations of geometric parameters and operating conditions. The post-processing of this huge amount of data allowed us to define the most effective geometric configuration, named baseline.
2017-09-04
Technical Paper
2017-24-0155
Marc Sens, Michael Guenther, Matthias Hunger, Jan Mueller, Sascha Nicklitzsch, Ulrich Walther, Steffen Zwahr
The combination of geometrically variable compression (VCR) and early intake valve closure (EIVC) proved to offer high potential for increasing efficiency of gasoline engines. While early intake valve closure reduces pumping losses, it is detrimental to combustion quality and residual gas tolerance due to a loss of temperature and turbulence. Large geometric compression ratio at part load compensates for the negative temperature effect of EIVC with further improving efficiency. By optimizing the stroke/bore ratio, the reduction in valve cross section at part load can result in greater charge motion and therefore in turbulence. Turbocharging means the basis to enable an increase in stroke/bore ratio, because the drawbacks at full load resulting from smaller valves can be only compensated by additional charge pressure.
2017-09-04
Technical Paper
2017-24-0157
Wolfgang Gross, Ahmad Rabanizada, Konstantin Markstädter, Harald Stoffels, Michael Bargende, Adrian Rienäcker
High combustion pressure in combination with high pressure gradient, as they e.g. can be evoked by high efficient combustion systems and e.g. by alternative fuels, acts as broadband excitation force which stimulates natural vibrations of piston, conrod and crankshaft during engine operation. Starting from the combustion chamber the assembly of piston, conrod and crankshaft and the main bearings represent the system of internal vibration transfer. To generate exact input and validation values for simulation models of structural dynamic and elastohydrodynamic coupled multi-body systems, experimental investigations are done. These are carried out on a 1.5-l inline four cylinder Euro 6 Diesel engine. The modal behavior of the system was examined in detail in simulation and test as a basis for the investigations. In an anechoic test bench combustion pressure, airborne and structure-borne noises are measured to identify the engine´s vibrational behaviour.
2017-09-04
Technical Paper
2017-24-0159
Davide Di Battista, Marco Di Bartolomeo, Carlo Villante, Roberto Cipollone
Internal combustion engines is actually one of the most important source of pollutants and greenhouse gases emissions. In particular, on-the-road transportation sector has taken this environmental challenge and worldwide governments set up regulations in order to limit the emissions and fuel consumption from vehicles. Among the several technologies under development, an ORC unit bottomed exhaust gas seems to be very promising, but it still has several complications when it is applied on board of a vehicle (weight, encumbrances, backpressure effect on the engine, safety, reliability). In this paper, a comprehensive mathematical model of an ORC unit bottomed a heavy duty engine, used for commercial vehicle, has been developed. The model is completed with the sizing of the two exchangers involved in the ORC plant: the heat recovery vapor generator (HRVG) and the condenser.
2017-09-04
Technical Paper
2017-24-0131
Sergio Mario Camporeale, Patrizia D. Ciliberti, Antonio Carlucci, Daniela Ingrosso
The incoming PostEuro6 regulation and the on-board diagnostics -OBD- pushes the research activity towards the set-up of even more efficient after treatment systems. Nowadays, the most common after treatment system for NOx reduction is the selective catalytic reactor –SCR- . This system requires as an input the value of engine out NOx emission –raw- in order to control the Urea dosing strategy. In this work, a grey box NOx raw emission model based on in-cylinder pressure signal (ICPS) is validated on two standard cycles: MNEDC and WLTC using an EU6 engine at the test bench. The overall results show a maximum relative error of the integrated cumulate value integral of 12.8% and 17.4% for MNEDC and WLTC respectively. In particular, the instantaneous value of relative error is included in the range of ± 10% in the steady state conditions while during transient conditions is less than 20% mainly.
2017-09-04
Technical Paper
2017-24-0139
Francesco Barba, Alberto Vassallo, Vincenzo Greco
The aim of the present study is to improve the effectiveness of the engine and aftertreatment calibration process through the critical evaluation of several methodologies available to estimate the soot mass flow produced by diesel engines and filtered by Diesel Particulate Filters (DPF). In particular, the focus of the present study has been the development of a reliable simulation method for the accurate prediction of the engine-out soot mass flow starting from Filter Smoke Number (FSN) measurements executed in steady state conditions, in order to predict the DPF loading considering different engine working conditions corresponding to NEDC and WLTP cycles. In order to achieve this goal, the study was split into two parts: - Correlation between ‘wet soot’ (measured by soot filter weighing) and the ‘dry soot’ (measured by the Micro Soot Sensor MSS).
2017-09-04
Technical Paper
2017-24-0146
Vincent Raimbault, Jerome Migaud, David Chalet, Michael Bargende, Emmanuel Revol, Quentin Montaigne
Upcoming regulations and new technologies are challenging the internal combustion engine and increase the pressure on car manufacturers to further reduce powertrain emissions. Indeed, RDE pushes engineering to keep low emissions not only at the bottom left of the engine map but in the complete range of load and engine speeds. This means for gasoline engines that the strategy used to increase the low end torque and power while moving out of lambda one conditions is no longer sustainable. For instance scavenging, which helps to increase the enthalpy at the turbine at low engine speed cannot be applied and thus leads to a reduction in low-end torque. Similarly, enrichment to keep the exhaust temperature sustainable in the exhaust tract components cannot be applied any more. The proposed study aims to provide a solution to keep the low end torque while maintaining lambda at 1. The tuning of the air intake system helps to improve the volumetric efficiency using resonance charging effects.
2017-09-04
Technical Paper
2017-24-0121
Ivan Arsie, Giuseppe Cialeo, Federica D'Aniello, Cesare Pianese, Matteo De Cesare, Luigi Paiano
The demand for high NOx conversion efficiency and low tailpipe ammonia slip for urea-based selective catalytic reduction (SCR) systems has substantially increased in the past decade, as NOx emission legislations for Diesel engines are becoming more stringent than ever before. Model-based control strategies are fundamental to meet the dual objective of maximizing NOx reduction and minimizing NH3 slip in urea-SCR catalysts. In this paper, a control oriented model of a Cu-zeolite urea-selective catalytic reduction (SCR) system for automotive diesel engines is presented. The model is derived from a quasi-dimensional four-state model of the urea-SCR plant. In order to make it suitable for the real-time urea-SCR management, a reduced order one-state model has been developed, with the aim of capturing the essential behavior of the system with a low computational demand. The model estimates the relevant species (i.e. NO, NO2 and NH3) independently.
2017-09-04
Technical Paper
2017-24-0130
Antonio Paolo Carlucci, Marco Benegiamo, Sergio Camporeale, Daniela Ingrosso
Nowadays, In-Cylinder Pressure Sensors (ICPS) have become a mainstream technology that promises to change the way the engine control is performed. Among all the possible applications, the prediction of raw (engine-out) NOx emissions would allow to eliminate the NOx sensor currently used to manage the after-treatment systems. In the current study, a semi-physical model already existing in literature for the prediction of engine-out nitric ox-ide emissions based on in-cylinder pressure measurement has been improved; in particular, the main focus has been to improve nitric oxide prediction accuracy when injection timing is varied. The main modification introduced in the model lies in taking into account the turbu-lence induced by fuel spray and enhanced by in-cylinder bulk motion.
2017-09-04
Technical Paper
2017-24-0128
Lauretta Rubino, Jan Piotr Oles, Antonino La Rocca
Environmental authorities such as EPA, VCA have enforced stringent emissions legislation governing air pollutants released into the atmosphere. Of particular interest is the challenges introduced by the limit on particulate number (PN) counting (#/km) and real driving emissions (RDE) testing; with the Euro 6c emissions legislation being shortly introduced for the gasoline direct injection engines. Gasoline particulate filters (GPF) are considered to be the most immediate solution. While engine calibration and testing over the NEDC allows the limits to be met, real driving emission and cold start represent a challenge. The present work focuses on an experimental durability study on road under real word driving conditions. Two set of experiments were carried out. The first study analyzed a Gasoline Particulate Filter (GPF) (2,4 liter, diameter 5,2” round) installed in underfloor (UF) position driven for up to 200.000 km.
2017-09-04
Technical Paper
2017-24-0098
Christophe Barro, Curdin Nani, Richard Hutter, Konstantinos Boulouchos
The operation of dual fuel engines, operated with natural gas as main fuel, offers the potential of substantial savings in CO2. Nevertheless, the operating map area where low pollutant emissions are produced is very narrow. Especially at low load, the raw exhaust gas contains high concentrations of unburned methane and, with high pilot fuel portions due to ignition limitations, also soot. The analysis of the combustion in those conditions in particular is not trivial, since multiple combustion modes are present concurrently. The present work focuses on the evaluation of the individual combustion modes of a dual fuel engine, operated with natural gas as main and diesel as pilot fuel, using a combustion model. The combustion has been split in two partwise concurrent combustion phases: the auto-ignition phase and the premixed flame propagation phase.
2017-09-04
Technical Paper
2017-24-0101
Pedro Marti-Aldaravi, Kaushik Saha, Jaime Gimeno, Sibendu Som
Actual combustion strategies in internal combustion engines rely on fast and accurate injection systems to be successful. One of the injector designs that has shown good performance over the past years is the direct-acting piezoelectric. This system allows precise control of the injector needle position and so the injected mass flow rate. Therefore, understanding how nozzle flow characteristics change as function of needle dynamics helps to choose the best lift law in terms of delivered fuel for a determined combustion strategy. Computational Fluid Dynamics is a useful tool for this task. In this work, nozzle flow of a prototype direct-acting piezoelectric has been simulated by using CONVERGE v2.3.10. Unsteady Reynolds-Averaged Navier-Stokes approach is used to take into account the turbulence. Simulations are able to properly capture the relationship between instantaneous partial needle lifts and the corresponding rate of injection.
2017-09-04
Technical Paper
2017-24-0103
Marlene Wentsch, Marco Chiodi, Michael Bargende
Main limiting factor in the application of 3D-CFD simulations within an engine development process is the very high time demand. The computing time of a 3D-CFD simulation is predominantly influenced by the number of cells within the computational mesh. An arbitrary cell coarsening, however, results in a distinct distortion of the simulation outcome. It is rather necessary to adapt the calculation models to the new mesh structure in order to ensure reliability and predictability of the 3D-CFD engine simulation. In the last decade, a fast response 3D-CFD tool was developed at FKFS in Stuttgart. It aims for a harmonized interaction between computational mesh, implemented calculation models and defined boundary conditions in order to enable fast running simulations for engine development tasks.
2017-09-04
Technical Paper
2017-24-0104
Daniel M. Nsikane, Kenan Mustafa, Andrew Ward, Robert Morgan, David Mason, Morgan Heikal
The Direct Numerical Simulation (DNS) approach to solving the fundamental transport equations down to the smallest scales of motion is favourable should the requirement be a truly predictive solution of fluid dynamic problems, but the simulation run times are unacceptable for most practical industrial applications. Despite the steadily increasing computational capabilities, Reynolds Averaged Navier-Stokes (RANS) based frameworks remain the only commercially viable option. The sub models within RANS simplify the description of key physical phenomena and include several numerical constants. These so-called “tuning constants” introduce multivariable dependencies that are almost impossible to untangle with local sensitivity studies. This paper addresses the prevailing difficulties in setting up an adequate Diesel spray simulation which arise from the mentioned multi-variable interactions of these “tuning constants”, by applying a statistical approach named Design of Experiments (DoE).
2017-09-04
Technical Paper
2017-24-0105
Stefania Falfari, Gian Marco Bianchi, Giulio Cazzoli, Claudio Forte PhD, Sergio Negro
The primary target of the internal combustion engines design is to lower the fuel consumption and to enhance the combustion process quality, in order to reduce the raw emission levels without performances penalty. In this scenario the direct injection system plays a key role for both diesel and gasoline engines. The spray dynamic behavior is crucial in defining the global and the local air index of the mixture, which in turns affects the combustion process development. At the same time the spray dynamic behavior is influenced by the cavitation process inside each single hole of the injector nozzle. The proper prediction of the cavitation development inside the injector nozzle holes is crucial in predicting the liquid jet emerging from them.
2017-09-04
Technical Paper
2017-24-0107
Alessandro Montanaro, Luigi Allocca, Vittorio Rocco, Michela Costa, Daniele Piazzullo
Enhancement of i.c. engine performances in terms of fuel economy and environment and human health preservation is an increasing key factor of the research in recent times. Mainly, that is due to the more and more stringent European and worldwide regulations tending to limit pollutant emissions to carbon monoxide, unburned hydrocarbons, nitrogen oxide, and particulate matter. Development of direct injection strategy (DI) in spark ignition (SI) engines partially fulfilled these tasks, as they run at higher compression ratios, with respect to port fuel injection (PFI), and operating with different injection strategies, so a greatest control over the air-to-fuel ratio is achieved. However, today the engines’ complexity and the number of sub-systems have increased, so the traditional techniques used for their optimization are often inadequate for the required challenges of high power output and low environmental impact.
2017-09-04
Technical Paper
2017-24-0113
Ezio Mancaruso, Luigi Sequino, Bianca Maria Vaglieco, Maria Cristina Cameretti
The management of multiple injections in compression ignition (CI) engines is one of the most common way to increase engine performance by avoiding hardware modifications and after-treatment systems. Great attention is given to the profile of the injection rate since it controls the fuel delivery in the cylinder. The Injection Rate Shaping (IRS) isa new developed technique that aims to manage the quantity of injected fuel during the injection process via a proper definition of the injection timing (injection duration and dwell time). In particular, it consists in closer and centered injection events and in a split main injection with a very small dwell time. From the experimental point of view, the performance of an IRS strategy has been studied in an optical CI engine. In particular, liquid and vapor phases of the injected fuel have been acquired via visible and infrared imaging, respectively. Injection parameters, like penetration and cone angle have been determined and analyzed.
2017-09-04
Technical Paper
2017-24-0090
Robert E. Morgan, Morgan Heikal, Emily Pike-Wilson
Urban air quality remains a major concern, in particular NOx and particle emission from diesel powered vehicles. Electrification offers a medium to long term solution, but there remains a need to significantly reduce internal combustion engine emissions in the short and medium term and potentially in the long term for long range inter city transportation. Late injection low temperature combustion (LTC) has the potential to achieve ultra-low emissions levels in a compression ignition engine by increasing the lean pre-mixed burn fraction. However, significant quantities of diluent are normally required to achieve the required delay in ignition and pre-mixing. This results in high boost requirements and increased pumping work negating the benefit of the LTC combustion strategy and increasing fuel consumption. Test results from a single cylinder light duty research engine are presented using a novel ramped combustion chamber.
Viewing 1 to 30 of 20246

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