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Viewing 1 to 30 of 111
2017-03-28
Technical Paper
2017-01-0970
Johann C. Wurzenberger, Christoph Triebl, Susanne Kutschi, Christoph Poetsch
Wall flow filters have successfully been used for many years to abate particulate matter emissions. Since then, modeling of this type of filter device has supported the development by a broad variety of approaches reaching from explicit pressure drop correlations up to complex 3D CFD simulations. 1D models are commonly used in the context of plant modeling supporting control development and calibration. Here most differences can be identified by the applied filtration, active or passive soot regeneration and catalytic reaction mechanisms. The proposed paper discusses a 1D+1D wall flow filter model resolving transport phenomena along the axial direction of the inlet/outlet channel and also in transverse direction through the soot cake and filter wall. The basic set of gas phase flow equations is extended by the passive transport of an arbitrary number of soot classes. The balance equations of deposit soot are extended to handle individual soot population.
2017-03-28
Technical Paper
2017-01-0969
Alois Danninger, Ismar Mustedanagic, Martin Herbst, Christoph Kreuzberger, Peter Lichtenberger, Armin Wabnig, Josef Zehetner, Georg Macher, Eric Armengaud
Reduction of fuel consumption and greenhouse gas emission is a challenge for our society as both targets shall be reached without drawback on mobility or freight transport. A promising approach to achieve this challenging target is the improvement of exhaust after-treatment control strategy – tightly coordinated with the respective engine. In this paper, a smart environment for the efficient validation of innovative exhaust after-treatment control strategies is proposed. The motivation is to provide a hybrid environment (mixing simulation and physical components) to reduce validation efforts and costs without impacting the representativeness of the test vectors.
2017-03-28
Technical Paper
2017-01-0634
Schoeffmann Wolfgang, Helfried Sorger, Siegfried Loesch, Wolfgang Unzeitig PhD, Thomas Huettner, Alois Fuerhapter
In order to achieve future CO2 targets - in particular under real driving conditions - different powertrain technologies will have to be introduced. Beside the increasing electrification of the powertrain, the utilization of the full potential of the internal combustion engine will be essential. In addition to further optimization steps on the combustion processes, reduction of mechanical losses and thermal- and energetic system consideration the Variable Compression Ratio (VCR) is probably the single measure with the highest potential. VCR systems are expected to gain a considerable share in next generation turbocharged SI engines in certain vehicle classes. The basic principle of the AVL VCR system explained in the paper is a 2-stage variation of the connecting rod length and thus the compression ratio.
2017-03-28
Technical Paper
2017-01-1331
Marko Basic, Thomas Resch
This paper describes a numerical study of the effect of hollow crankshafts on crankshaft local strength and durability as well as slider bearing contact behavior. Crankshaft dynamic simulation for durability is still a challenging task, although numerical methods are already worldwide established and integrated part of nearly every standard engine development process. Such standard methods are based on flexible multi-body dynamic simulation, combined with Finite Element analysis and multi-axial fatigue evaluation. They use different levels of simplification and consider the most influencing phenomena relevant for durability. Lightweight design and downsizing require more and more detailed methods due to higher deformation of the crankshaft. This is especially true for hollow shafts, as present in motorsport design or aerospace applications, but also for standard engine having high potential for significant weight savings.
2017-03-28
Technical Paper
2017-01-0517
Ivan Taritas, Darko Kozarac, Momir Sjeric, Miguel Sierra Aznar, David Vuilleumier, Reinhard Tatschl
This paper presents a newly developed quasi-dimensional multi-zone dual fuel combustion model, which has been integrated within the commercial engine system simulation framework. Model is based on the modified Multi-Zone Combustion Model and Fractal Combustion Model. Modified Multi-Zone Combustion Model handles the part of the combustion process that is governed by the mixing-controlled combustion, while the modified Fractal Combustion Model handles the part that is governed by the flame propagation through the combustion chamber. The developed quasi-dimensional dual fuel combustion model features phenomenological description of spray processes, i.e. liquid spray break-up, fresh charge entrainment, droplet heat-up and evaporation process. In order to capture the chemical effects on the ignition delay, special ignition delay table has been made.
2017-03-28
Technical Paper
2017-01-1110
Muammer Yolga
With the introduction of new regulations on emissions, fuel efficiency and driving cycles, challenges for the powertrains are significantly increasing to a new level. During the transition phase for these new targets, hybrid-electric powertrains are an unquestioned option for short and long-term solutions. Hybridization however, not only brings benefits on these challenging efficiency or emission targets, but also allows numerous new possibilities on controls of different powertrain elements as well as new approaches of design of powertrain elements. A good example is transmissions where, hybridization allows a new transmission type called Dedicated Hybrid Transmission (DHT), which enables to use novel control strategies bringing improved performance, driveability, durability and NVH behavior. This paper focuses on the novel shift strategy where friction clutches do not have to slip.
2017-03-28
Technical Paper
2017-01-0547
Zvonimir Petranovic, Wilfried Edelbauer, Milan Vujanović PhD, Peter Priesching, Reinhard Tatschl, Neven Duić PhD
In this research the modelling of the reactive sprays process within the compression ignition CI engine combustion chamber is performed. Several engine operating conditions are researched and thoroughly analyzed. Usually, the spray process is modeled with the Euler Lagrangian approach which has limited validity in the dense spray region near the nozzle exit. In the presented research a new method has been developed and used within the 3-D RANS CFD modeling framework. The spray process is modelled with the Euler Eulerian size-of-classes model used for reliable interphase momentum transfer. Furthermore, the combustion process is modelled by taking into account chemical kinetics solving the general gas phase reaction equations. The new method is incorporated into the commercial Computational Fluid Dynamics (CFD) code FIRE®, and it was used in combination with the previously validated spray sub-models.
2017-03-28
Technical Paper
2017-01-0621
Sanjin Saric, Andreas Ennemoser, Branislav Basara, Heinz Petutschnig, Christoph Irrenfried, Helfried Steiner, Günter Brenn
RANS computations of heat transfer involving wall bounded flows at elevated Prandtl numbers typically suffer from a lack of accuracy and/or increased mesh dependency. This can be often attributed to an improper near-wall turbulence modeling and the deficiency of the wall heat transfer models (based on the so called P-functions) that do not properly account for the variation of the turbulent Prandtl number in the wall proximity (y+<5) [1]. As the conductive sub-layer gets significantly thinner than the viscous velocity sub-layer (for Pr >1), treatment of the thermal buffer layer gains importance as well. Various hybrid strategies utilize blending functions dependent on the molecular Prandtl number, which do not necessarily provide a smooth transition from the viscous/conductive sub-layer to the logarithmic region [2].
2017-01-10
Technical Paper
2017-26-0137
Marco Schöggl, Ernst-Georg Lorinser
Abstract With the official publication of the “RDE package 1” on 31st March 2016 the long awaited start of RDE testing is now fixed. This event marks a milestone in the emission legislation for passenger cars and is the first of a series of four RDE packages to fade-in real world testing of passenger cars in Europe. During the same time India announced in the Gazette of India on 19th February, 2016 - G.S.R. 187(E). - the draft of introduction of Bharat VI by April 1st 2020 [5] which also should include the Real Driving Emissions (RDE) on-road certification as per procedure laid down in AIS137 and as amended from time to time. As European RDE legislation will be the baseline for Indian RDE legislation rules this paper will highlight the differences and challenges expected between the requirements in Europe compared to India during the first tests done by AVL Technical Center Private Limited located in Gurgaon.
2016-11-08
Journal Article
2016-32-0043
Bernhard J. Graf, Christian Hubmann, Markus Resch, Mehdi Mehrgou
Abstract Beside hard facts as performance, emissions and fuel consumption especially the brand specific attributes such as styling and sound are very emotional, unique selling prepositions. To develop these emotional characters, within the given boundary conditions of the future pass-by regulation, it is necessary to define them at the very beginning of the project and to follow a consequent development process. The following paper shows examples of motorcycle NVH development work on noise cleaning and sound engineering using a hybrid development process combining front loading, simulation and testing. One of the discussed solutions is the investigation of a piston pin offset in combination with a crankshaft offset for the reduction of friction. The optimization of piston slap noise as a result of the piston secondary motion was performed by simulation. As another example a simulation based development was performed for the exhaust system layout.
2016-06-15
Technical Paper
2016-01-1802
Mehdi Mehrgou, Franz Zieher, Christoph Priestner
Abstract Recently, hybrid and fully electric drives have been developing widely in variety, power and range. The new reliable simulation approaches are needed, in order to meet the defined NVH targets of these systems and implementing CAE methods for front loading, Design Validation Process (DVP). This paper introduces the application of a novel NVH analysis workflow on an electric vehicle driveline including both electromagnetic and mechanical excitations for an absolute evaluation of the NVH performance. At first, the electromagnetic field is simulated using FEM method to extract the excitations on the stator, rotor bearings as well as the drive torque. Then, the multibody dynamic model of the driveline is built-up, driven by this torque. The effect of eccentricity and skew angle of rotor in electromagnetic excitations are shown.
2016-06-15
Technical Paper
2016-01-1761
Antonio Acri, Guenter Offner, Thomas Resch, Eugene Nijman, Roberto Corradi
Abstract For vibration and acoustics vehicle development, one of the main challenges is the identification and the analysis of the noise sources, which is required in order to increase the driving comfort and to meet the stringent legislative requirements for the vehicle noise emission. Transfer Path Analysis (TPA) is a fairly well established technique for estimating and ranking individual low-frequency noise or vibration contributions via the different transmission paths. This technique is commonly applied on test measurements, based on prototypes, at the end of the design process. In order to apply such methodology already within the design process, a contribution analysis method based on dynamic substructuring of a multibody system is proposed with the aim of improving the quality of the design process for vehicle NVH assessment and to shorten development time and cost.
2016-06-15
Technical Paper
2016-01-1837
Stephan Brandl, Werner Biermayer, Bernhard Graf, Thomas Resch
Abstract Due to more stringent emission regulation, especially plug-in hybrid vehicles have an increased attractiveness for OEMs to reduce OEM’s CO2 fleet emission. Generally, hybrid vehicles have a much higher complexity than conventional vehicles. This gives an additional degree of freedom for the development but also increases the number of potential NVH topics dramatically. Therefore, the role of frontloading and early prototype testing is getting even higher importance than in standard developments. Current hybrid vehicles on the market are mainly ICE vehicles with electric boosting or starting functionality only. This however will not be sufficient to fulfill the OEM’s CO2 fleet emission requirements. Future hybrid vehicles will have much higher electrical capabilities and drive much more in pure electric modes. Therefore, the more frequent change between the different driving modes and the related mode transitions will lead to a more complex interior NVH situation.
2016-06-15
Technical Paper
2016-01-1775
Thomas Resch, Oliver Knaus, Siegmund Thomann, Stephan Brandl
Abstract Modern powertrain noise investigation in the development process and during trouble shooting is a combination of experiment and simulation. In simulation in recent years main focus was set on model completeness, consideration of all excitation mechanisms and efficient and stabile numerical algorithms. By that the total response of the virtual powertrain is already comparable to the overall noise level of the real powertrain. Actual challenge is to trace back the overall response to its main excitation and noise generating mechanism as well as to their main driving parameters to support the engineer not only in reaching absolute values, but also to derive the root cause of a response or potential problem and to get hints on how to improve the specific behavior. Approaches by parameter sensitivity studies are time consuming and not unambiguous.
2016-06-15
Journal Article
2016-01-1817
Juergen Veit, Paco Langjahr, Stephan Brandl, Bernhard Graf
Abstract Due to more challenging future emission legislations and the trend towards downsizing, the number of turbocharged (TC) engines, especially petrol engines, is steadily increasing. The usage of TC has high risk to cause different noise phenomena apparent in the vehicle interior which are often perceived as annoying for the passengers. In order to further improve consideration of TC topics in the development, objective judgment and monitoring of TC noise issues is of high importance. Therefore, objective parameters and corresponding tools that are especially focusing on TC noise phenomena have to be developed. One main target of these tools is to deliver an objective TC assessment in an efficient way and with minimum additional effort. Application of the criteria presented in this publication therefore allows acoustic engineers to judge the NVH behavior and annoyance of the TC with respect to its vehicle interior noise contribution.
2016-04-05
Technical Paper
2016-01-0201
Armin Traussnig, Wilko Jansen, Heinz Petutschnig, Sepp Steiner, Petra Gruen
Abstract In order to meet current and future emission and CO2 targets, an efficient vehicle thermal management system is one of the key factors in conventional as well as in electrified powertrains. Global vehicle simulation is already a well-established tool to support the vehicle development process. In contrast to conventional vehicles, electrified powertrains offer an additional challenge to the thermal conditioning: the durability of E-components is not only influenced by temperature peaks but also by the duration and amplitude of temperature swings as well as temperature gradients within the components during their lifetime. Keeping all components always at the preferred lowest temperature level to avoid ageing under any conditions (driving, parking, etc.) will result in very high energy consumption which is in contradiction to the efficiency targets.
2016-04-05
Technical Paper
2016-01-0558
Christoph Poetsch, Tomaz Katrasnik
Abstract The present work introduces an innovative mechanistically based 0D spray model which is coupled to a combustion model on the basis of an advanced mixture controlled combustion approach. The model calculates the rate of heat release based on the injection rate profile and the in-cylinder state. The air/fuel distribution in the spray is predicted based on momentum conservation by applying first principles. On the basis of the 2-zone cylinder framework, NOx emissions are calculated by the Zeldovich mechanism. The combustion and emission models are calibrated and validated with a series of dedicated test bed data specifically revealing its capability of describing the impact of variations of EGR, injection timing, and injection pressure. A model based optimization is carried out, aiming at an optimum trade-off between fuel consumption and engine-out emissions. The findings serve to estimate an economic optimum point in the NOx/BSFC trade-off.
2016-04-05
Technical Paper
2016-01-0718
Mattias Mayer, Peter Hofmann, Bernhard Geringer, John Williams, James Moss, Paul Kapus
Abstract In recent years concern has arisen over a new combustion anomaly, which was not commonly associated with naturally aspirated engines. This phenomenon referred to as Low-Speed Pre-Ignition (LSPI), which often leads to potentially damaging peak cylinder pressures, is the most important factor limiting further downsizing and the potential CO2 benefits that it could bring. Previous studies have identified several potential triggers for pre-ignition where engine oil seems to have an important influence. Many studies [1], [2] have reported that detached oil droplets from the piston crevice volume lead to auto-ignition prior to spark ignition. Furthermore, wall wetting and subsequently oil dilution [3] and changes in the oil properties by impinging fuel on the cylinder wall seem to have a significant influence in terms of accumulation and detachment of oil-fuel droplets in the combustion chamber.
2016-04-05
Journal Article
2016-01-0969
Johann C. Wurzenberger, Sophie Bardubitzki, Susanne Kutschi, Robert Fairbrother, Christoph Poetsch
The present work introduces an extended particulate filter model focusing on capabilities to cover catalytic and surface storage reactions and to serve as a virtual multi-functional reactor/separator. The model can be classified as a transient, non-isothermal 1D+1D two-channel model. The applied modeling framework offers the required modeling depth to investigate arbitrary catalytic reaction schemes and it follows the computational requirement of running in real-time. The trade-off between model complexity and computational speed is scalable. The model is validated with the help of an analytically solved reference and the model parametrization is demonstrated by simulating experimentally given temperatures of a heat-up measurement. The detailed 1D+1D model is demonstrated in a concept study comparing the impact of different spatial washcoat distributions.
2015-11-17
Technical Paper
2015-32-0740
Christian Hubmann, Hubert Friedl, Stefan Gruber, Nigel Foxhall
The automotive trend towards increased levels of electrification is showing a clear direction for hybrid technologies. Nowadays Mild- and plug-in-hybrids open a very wide area of future developments whereas battery electric vehicles (BEV) are still evident but still perceived as niche products with limited production volumes. Nevertheless, major OEMs are working on these kinds of vehicles and have also brought such EV concepts into series production. All of these designs show a clear trend that, beside the topic of electric traction motor and energy storage systems, the internal combustion engine (ICE) is also coming into focus again. In many of these vehicles the range extender (RE) unit is foreseen as an emergency unit to recharge the batteries if the state of charge (SOC) is too low. One of the major advantages of a BEV over other designs is the very good acoustic behavior, so the NVH performance becomes the most challenging topic for RE development.
2015-09-06
Journal Article
2015-24-2532
Reinhard Ratzberger, Thomas Kraxner, Jochen Pramhas, Klaus Hadl, Helmut Eichlseder, Ludwig Buergler
Abstract The continuously decreasing emission limits lead to a growing importance of exhaust aftertreatment in Diesel engines. Hence, methods for achieving a rapid catalyst light-off after engine cold start and for maintaining the catalyst temperature during low load operation will become more and more necessary. The present work evaluates several valve timing strategies concerning their ability for doing so. For this purpose, simulations as well as experimental investigations were conducted. A special focus of simulation was on pointing out the relevance of exhaust temperature, mass flow and enthalpy for these thermomanagement tasks. An increase of exhaust temperature is beneficial for both catalyst heat-up and maintaining catalyst temperature. In case of the exhaust mass flow, high values are advantageous only in case of a catalyst heat-up process, while maintaining catalyst temperature is supported by a low mass flow.
2015-09-06
Technical Paper
2015-24-2387
Emiliano Vitaliani, Daniele Di Rocco, Martin Sopouch
Abstract The aim of this paper is the study of the Centrifugal Pendulum Vibration Absorber (CPVA) dynamic behavior, with the background of improved vibration isolation and damping quality through a wide range of operating speeds. The CPVAs are passive devices, which are used in rotating machinery to reduce the torsional vibration without decreasing performance. After a first use of these damping systems in the field of aeronautics, nowadays CPVAs are employed also in railway and automotive applications. In principle, the CPVA is a mass, mounted on a rotor, which moves along a defined path relative to the rotor itself, driven by centrifugal effects and by the rotor's torsional vibrations. The advantage that such absorbers provide is the capability to counteract torsional vibrations arising with frequencies proportional to the mean operating speed. This is in particular the case with Internal Combustion Engines (ICE) where the induced vibrations are caused by the combustions process.
2015-09-06
Technical Paper
2015-24-2526
Borislav Klarin, Thomas Resch, Chiara Sessarego, Giorgio Spanu, Gianni Lamonaca
This paper presents a methodology for numerical investigation of a full flexible balancer drive together with engine and crank train under realistic operating conditions where shaft dynamics, gear contact and rattle impacts, gear root stresses and friction losses in bearings and gear interaction are taken into account and can be balanced against each other to achieve the design criteria. Gear rattle is driven by the speed fluctuation of the crank train, the resistance torque (mainly friction), shaft inertia and the backlash in the gears. The actual trend to engine downsizing and up-torqueing increases the severity to rattle as engines are running on higher combustion pressures. This increases torque and speed fluctuation, which makes the detailed investigation in this torque transfer even more demanding. A common method to reduce gear rattle is the usage of so-called scissors gears.
2015-04-14
Technical Paper
2015-01-0932
Satoru Sasaki, Masaaki Kato, Takamasa Yokota, Mitsuru Konno, Denis Gill
Abstract DiMethyl Ether (DME) has been known to be an outstanding fuel for combustion in diesel cycle engines for nearly twenty years. DME has a vapour pressure of approximately 0.5MPa at ambient temperature (293K), thus it requires pressurized fuel systems to keep it in liquid state which are similar to those for Liquefied Petroleum Gas (mixtures of propane and butane). The high vapour pressure of DME permits the possibility to optimize the fuel injection characteristic of direct injection diesel engines in order to achieve a fast evaporation and mixing with the charged gas in the combustion chamber, even at moderate fuel injection pressures. To understand the interrelation between the fuel flow inside the nozzle spray holes tests were carried out using 2D optically accessed nozzles coupled with modelling approaches for the fuel flow, cavitation, evaporation and the gas dynamics of 2-phase (liquid and gas) flows.
2015-04-14
Technical Paper
2015-01-1630
Wolfgang Ebner, Michael Stolz, Markus Bachinger, Evgeny Korsunsky
Abstract Hybrid-electric vehicles provide additional functionality compared to conventional vehicles. So-called ‘hybrid’ software functions are required to coordinate the conventional powertrain control and these additional control functions. A key factor to reduce the fuel consumption lies in optimal control of the entire interconnected powertrain. This paper aims to provide a framework for efficient interface definition, connection and coordination of control units for hybrid electric vehicles. Such a framework supports an efficient development of control unit architectures and the distribution of software functions. The generic approach necessitates modular software functions. It defines the distribution of these functions in control units optimized with respect to reuse, interfaces and compatibility with different powertrain topologies and electrification variants, especially also considering compatibility with a conventional powertrain and its electric hybridization.
2015-04-14
Technical Paper
2015-01-1197
Chao Chen, Franz Diwoky, Zoran Pavlovic, Johann Wurzenberger
This paper presents a system-level thermal model of a fluid-cooled Li-Ion battery module. The model is a reduced order model (ROM) identified by results from finite element analysis (FEA)/computational fluid dynamic (CFD) coupling simulation using the linear and time-invariant (LTI) method. The ROM consists of two LTI sub-systems: one of which describes the battery temperature response to a transient battery current, and the other of which takes into account of the battery temperature variation due to a heat flux induced by a varied inlet temperature of the battery cooling circuit. The thermal LTI model can be coupled to an electrical model to build a complete system-level battery ROM. Test examples show that the ROM is able to provide as accurate results as those from FEA/CFD coupling simulations.
2015-04-14
Technical Paper
2015-01-1275
Wolfgang Johann Schoeffmann, Caroline Truffinet, Michael Howlett, Norbert Ausserhofer, Andreas Zurk
Abstract When designing a new internal combustion engine, the choice of technology for the timing drive system is one of the key decisions that determines the overall characteristics of the engine with far reaching implications on the remaining architecture and overall packaging of the engine. For Passenger car engines there are two mainstream technologies: toothed belts and chains. Each of these offers several sub-variants, such as dry vs. wet belt, or toothed vs. roller chain. This paper examines the differences between these technologies in relation to the key engine attributes including package, cost, weight, durability, NVH and frictional losses. A quantitative evaluation is made where possible, based on data collected from recent engine development programs, backed up by literature study and data from the component supply industry.
2015-04-14
Technical Paper
2015-01-1625
Frederic Boissinot, Jerome Bellavoine, Andrew Shabashevich, Siegfried Puster
Abstract Today, OEMs are challenged with an increasing number of powertrain variants and complexity of controls software. They are facing internal pressure to provide mature and refined calibrations earlier in the development process. Until now, it was difficult to respond to these requests as the drivability's calibration tasks are mostly done in vehicles. This paper describes a new methodology designed to answer these challenges by performing automated shift quality calibration prior to the availability of vehicles. This procedure is using a powertrain dynamometer coupled with a real-time vehicle dynamics model. By using a Power Train Test Bed (PTTB), a physical vehicle is not required. As soon as the vehicle dynamics model and its parameters have been defined, it can be simulated on the PTTB and drivability calibrations can be developed. A complete powertrain is coupled with low inertia and highly dynamic dynamometers.
2015-04-14
Technical Paper
2015-01-1358
Matthias Rainer, Gundolf Haase, Branislav Basara, Guenter Offner
Abstract The aim of this paper is to present the adjoint equations for shape optimization derived from steady incompressible Navier-Stokes (N-S) equations and an objective functional. These adjoint Navier-Stokes equations have a similar form as the N-S equations, while the source terms and the boundary conditions depend on the chosen objective. Additionally, the gradient of the targeted objective with respect to the design variables is calculated. Based on this, a modification of the geometry is computed to arrive at an improved objective value. In order to find out, whether a more sophisticated approach is needed, the adjoint equations are derived by using two different approaches. The first approach is based on the frozen turbulence assumption and the second approach, which is advanced in this paper, is derived from the near wall k − ζ − f turbulence model.
2015-04-14
Technical Paper
2015-01-1247
Johann C. Wurzenberger, Christoph Poetsch
Abstract Direct injection Diesel engines are a propulsion technology that is continuously developed to meet emission standards. Great optimization potential lies in the combustion process itself. The application of closed loop combustion control allows reacting online to environmental conditions and stabilizing the combustion regarding performance and emissions. Dedicated real-time plant models help to develop and calibrate control algorithms in office and hardware in the loop environments. The present work describes a real-time capable, crank-angle resolved engine, cylinder and combustion model. The cylinder applies an 0D, two-zone approach and a phenomenological combustion model describes ignition delay, premixed and diffusive combustion. The latter is enhanced by a quasi-dimensional description of the injection spray. The model is validated with dedicated measurements. The plant model is applied in two use-cases for closed loop combustion control.
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