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Viewing 1 to 30 of 74
Technical Paper
2014-06-30
Vishal Parmar, Daniele Di Rocco, Martin Sopouch, Philippe Albertini
Over the past 30 years simulation of the N&V (Noise and Vibration) behavior of automotive drivelines became an integral part of the powertrain development process. With current and future HEVs (Hybrid-Electrical Vehicles) additional phenomena and effects have been entered the scene and need to be taken into account during layout/design as well as optimization phase. Beside effects directly associated with the e-components (namely electric whistle and whine), torque changes caused by activation/deactivation of the e-machine give rise to vibration issues (e.g. driveline shuffle or clonk) as well. This is in particular true for transient operation conditions like boosting and recuperation. Moreover, aspects of starting the Internal Combustion Engine (ICE) using the built-in e-machine in conjunction with the dynamic behavior of torsional decoupling devices become increasingly important. In order to cope with above mentioned effects a multi-physics simulation approach is required. The following paper proposes a simulation approach which incorporates the domains of the ICE thermodynamics, the mechanical driveline system, the electric components, the vehicle, as well as the fundamental control functions.
Technical Paper
2014-06-30
Alois Sontacchi, Matthias Frank, Franz Zotter, Christian Kranzler, Stephan Brandl
Today, the number of downsized engines with two or three cylinder engines is increasing due to an increase in fuel efficiency. However, downsized engines exhibit unbalanced interior sound in the range of their optimal engine speed, largely because of their dominant engine orders. In particular, the sound of two-cylinder engines yields half the perceived engine speed of an equivalent four-cylinder engine at the same engine speed. As a result when driving, the two-cylinder engine would be shifted to higher gears much later, diminishing the expected fuel savings. This contribution presents an active in-car sound generation system that makes a two-cylinder engine sound like the more familiar four-cylinder engine. This is done by active, load-dependent playback of signals extracted from the engine vibration through a shaker mounted on the firewall. A blind test with audio experts indicates a significant reduction of the engine speed when shifting to a higher gear. In the blind test, experts favored the interior sound of the proposed sound generation system and perceived better interaction with the vehicle.
Technical Paper
2014-06-30
Matthias Frank, Franz Zotter, Alois Sontacchi, Stephan Brandl, Christian Kranzler
When employing in-car active sound generation (ASG) and active noise cancellation (ANC), the accurate knowledge of the vehicle interior sound pressure distribution in magnitude as well as phase is paramount. Revisiting the ANC concept relevant boundary conditions in spatial sound fields will be addressed. Moreover, within this study the controllability and observability requirements in case of ASG and ANC were examined in detail. This investigation focuses on sound pressure measurements using a 24 channel microphone array at different heights near the head of the driver. A shaker at the firewall and four loudspeakers of an ordinary in-car sound system have been investigated in order to compare their sound fields. Measurements have been done for different numbers of passengers, with and without a dummy head and real person on the driver seat. Transfer functions have been determined with a log-swept sine technique. According to the measurements, the shape of the sound field produced by the shaker is more balanced than one produced by the loudspeakers, albeit the shaker’s frequency response is limited to low frequencies.
Technical Paper
2014-06-30
Michael Klanner, Mathias Mair, Franz Diwoky, Oszkar Biro, Katrin Ellermann
The noise vibration and harshness (NVH) simulation of electric machines becomes increasingly important due to the use of electric machines in vehicles. This paper describes a method to reduce the calculation time and required memory of the finite element NVH simulation of electrical machines. The stator of a synchronous electrical machine is modeled as a two-dimensional problem to reduce investigation effort. The electromagnetic forces acting on the stator are determined by FE-simulation in advance. Since these forces need to be transferred from the electromagnetic model to the structural model, a coupling algorithm is necessary. In order to reduce the number of nodes, which are involved in the coupling between the electromagnetic and structural model, multipoint constraints (MPC) are used to connect several coupling nodes to one new coupling node. For the definition of the new coupling nodes, the acting load is analyzed with a 2D-FFT. After the coupling with MPCs, forces are only acting on the newly defined coupling nodes.
Technical Paper
2014-06-30
Alexander Ulz, Alfred Rust, Bernhard Graf, Alois Sontacchi
Due to future directives of the European Union regarding fuel consumption and CO2 emissions the automobile industry is forced to develop new and unconventional technologies. These include for example start-stop-systems, cylinder deactivation or even reduction of the number of cylinders, which however lead to unusual acoustical experiences and customer complaints. Therefore it is necessary to evaluate the sound character of engines with low numbers of cylinders (2 and 3 cylinders) and also the differences to the character of the more common 4-cylinder engines. Psychoacoustic parameters are used to describe and understand the differences and to derive possible potentials for improvement. The used data base consists of artificial head recordings of car interior noise according to defined driving states measured on the AVL test track. Naturally, there are much more recordings available for 4-cylinder engines than for 2- and 3-cylinder engines. This has to be taken into account in the statistical evaluations.
Technical Paper
2014-04-01
Chao Chen, Martin Mohr, Franz Diwoky
Abstract This work presents a physical model that calculates the efficiency maps of the inverter-fed Permanent Magnet Synchronous Machine (PMSM) drive. The corresponding electrical machine and its controller are implemented based on the two-phase (d-q) equivalent circuits that take into account the copper loss as well as the iron loss of the PMSM. A control strategy that optimizes the machine efficiency is applied in the controller to maximize the possible output torque. In addition, the model applies an analytical method to predict the losses of the voltage source inverter. Consequently, the efficiency maps within the entire operating region of the PMSM drive can be derived from the simulation results, and they are used to represent electric drives in the system simulation model of electric vehicles (EVs).
Technical Paper
2014-04-01
Armin Traussnig, Heinz Petutschnig, Andreas Ennemoser, Michael Stolz, Mauro Tizianel
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. Furthermore the increasing number of vehicle configurations leads to a high variability and degrees of freedom in possible system designs and the control thereof, which can only be handled by a comprehensive tool chain of vehicle system simulation and a generic control system architecture. The required model must comprise all relevant systems of the vehicle (control functionality, cooling system, lubrication system, engine, drive train, HV components etc.). For proper prediction with respect to energy consumption all interactions and interdependencies of those systems have to be taken into consideration, i.e. all energy fluxes (mechanical, hydraulically, electrical, thermal) have to be exchanged among the system boundaries accordingly. However, it is very important that the level of detail of the VTMS model fits to the current phase of the vehicle development process.
Technical Paper
2014-04-01
Johann C. Wurzenberger, Tomaz Katrasnik
This works presents a real-time capable simulation model for dual fuel operated engines. The computational performance is reached by an optimized filling and emptying modeling approach applying tailored models for in-cylinder combustion and species transport in the gas path. The highly complex phenomena taking place during Diesel and gasoline type combustion are covered by explicit approaches supported by testbed data. The impact of the thermodynamic characteristics induced by the different fuels is described by an appropriate set of transport equations in combination with specifically prepared property databases. A thermodynamic highly accurate 6-species approach is presented. Additionally, a 3-species and a 1-species transport approach relying on the assumption of a lumped fuel are investigated regarding accuracy and computational performance. The comparison of measured and simulated pressure and temperature traces shows very good agreement. The real-time factor of a 6 cylinder medium speed engine is in the range of 0.2 for all species transport approaches, enabling the support of HiL based function development and calibration.
Technical Paper
2014-04-01
Aleš Kolar, Ralf Cerna, Werner Hofegger, Christoph Pichler, Markus Riener, Nathan Murphy, Georg Zembacher
The correct information about legal demands of the On-Board-Diagnostic (OBD) system in a vehicle project is required throughout the entire development process. Usually, the main obstacle in succeeding is to provide the company's expertise of some few experts for all employees who work in OBD related projects. The paper describes the AVL solution for knowledge management and tool supported control system design and calibration: OBD System Development Database. The software enables the user to access the regulatory requirements for a specific application and legislation from past, present and future (proposed rule-making) point of view. Information concerning already available and stored monitoring concepts is linked to the requirements in order to re-use potentially suitable concepts and to enable an efficient knowledge exchange within the company. Also, various reporting functionalities are implemented, for example the listing and comparison of legal requirements and monitoring concepts.
Technical Paper
2014-04-01
Rok Kopun, Dongsheng Zhang, Wilfried Edelbauer, Bernhard Stauder, Branislav Basara, David Greif
In this paper, a recently improved Computational Fluid Dynamics (CFD) methodology for virtual prototyping of the heat treatment of cast aluminum parts, above most of cylinder heads of internal combustion engines (ICE), is presented. The comparison between measurement data and numerical results has been carried out to simulate the real time immersion quenching cooling process of realistic cylinder head structure using the commercial CFD code AVL FIRE®. The Eulerian multi-fluid modeling approach is used to handle the boiling flow and the heat transfer between the heated structure and the sub-cooled liquid. While for the fluid region governing equations are solved for each phase separately, only the energy equation is solved in the solid region. Heat transfer coefficients depend on the boiling regimes which are separated by the Leidenfrost temperature. The objective of the present research work is to present an update of the quenching model where instead of constant, variable Leidenfrost temperature is applied.
Technical Paper
2014-04-01
David Greif, Wilfried Edelbauer, Jure Strucl
Abstract The paper addresses aspects of modeling cavitating flows within high pressure injection equipment while considering the effects of liquid compressibility. The presented numerical study, performed using the commercial CFD code AVL FIRE®, mimics common rail conditions, where the variation in liquid density as a function of pressure may be relevant owing to very high pressure injection scenarios. The flow through the injector has been calculated and the conditions at the outlet of the nozzle orifice have been applied as inlet condition for subsequent Euler-Lagrangian spray calculations to investigate the effects of liquid compressibility treatment on spray propagation. Flows of such nature are of interest within automotive and other internal combustion (IC) related industries to obtain good spray and emissions characteristics. In the development process of the injection equipment, predictive methods using Computational Fluid Dynamics (CFD) contribute to lower development costs, improved engine efficiency, decreased emissions and nevertheless shorter development cycles.
Technical Paper
2014-04-01
Christoph Poetsch
Abstract The present works presents a real-time capable engine model with physical based description of the fuel injection and the combustion process. The model uses a crank-angle resolved cylinder model and a filling and emptying approach for cylinder and gas-path interaction. A common rail injection system model is developed and implemented into the real-time engine framework. The injection model calculates injection quantity and injection rate profile from the input of the ECU signals target injection pressure and injection timing. The model accounts for pressure oscillations in the injection system. A phenomenological combustion model for Diesel engines is implemented, which is based on the mixing controlled combustion modeling approach. The combustion model calculates the rate of heat release from the injection rate given by the injection model. The injection and combustion model are validated in detail against steady-state measurement data for two different passenger car sized engines.
Technical Paper
2013-09-24
Juergen Rechberger, Andreas Kaupert, Christoffer Graae Greisen, Jonas Hagerskans, Ludger Blum
The DESTA project, funded by the European Commission under the FCH JU program, is a collaborative effort of AVL List GmbH, Eberspächer Climate Control Systems, Topsoe Fuel Cell (TOFC), Volvo and Forschungszentrum Jülich to bring fuel cell based auxiliary power units (APU) for heavy duty truck idling elimination closer to the market. Within this project Solid Oxide Fuel Cell (SOFC) technology is used, which enables the use of conventional diesel fuel. During the project the technology is significantly optimized and around 10 APU systems are thoroughly tested. In 2014 a vehicle demonstration on board of a US type Volvo class 8 truck will be performed.
Technical Paper
2013-09-08
Christoph Poetsch, Henrik Schuemie, Herwig Ofner, Reinhard Tatschl, Oldrich Vitek
In spark-ignition engines, fluctuations of the in-cylinder pressure trace and the apparent rate of heat release are usually observed from one cycle to another. These Cycle-to-Cycle Variations (CCV) are affected by the early flame development and the subsequent flame front propagation. The CCV are responsible for engine performance (e.g. fuel consumption) and the knock behavior. The occurrence of the phenomena is unpredictable and the stochastic nature offers challenges in the optimization of engine control strategies. In the present work, CCV are analyzed in terms of their impact on the engine knock behavior and the related efficiency. Target is to estimate the possible fuel consumption savings in steady-state operation and in the drivecycle, when CCV are reduced. Since CCV are immanent on real engines, such a study can only be done by means of simulation. For the analysis different tools are applied, from 1-D gas dynamic models with detailed combustion modeling to real-time capable engine and vehicle system simulation.
Technical Paper
2013-09-08
Valdas Caika, Peter Sampl, David Greif
To promote advanced combustion strategies complying with stringent emission regulations of CI engines, computational models have to accurately predict the injector inner flow and cavitation development in the nozzle. This paper describes a coupled 1D/2D/3D modeling technique for the simulation of fuel flow and nozzle cavitation in diesel injection systems. The new technique comprises 1D fuel flow, 2D multi-body dynamics and 3D modeling of nozzle inner flow using a multi-fluid method. The 1D/2D model of the common rail injector is created with AVL software Boost-Hydsim. The computational mesh including the nozzle sac with spray holes is generated with AVL meshing tool Fame. 3D multi-phase calculations are performed with AVL software FIRE. The co-simulation procedure is controlled by Boost-Hydsim. Initially Hydsim performs a standalone 1D simulation until the needle lift reaches a prescribed tolerance (typically 2 to 5 μm). From this time instant the 1D/2D/3D co-simulation with the FIRE multiphase solver is started.
Technical Paper
2013-04-08
Jacob Swanson, David Kittelson, Barouch Giechaskiel, Alexander Bergmann, Martyn Twigg
The European Emissions Stage 5b standard for diesel passenger cars regulates particulate matter to 0.0045 g/km and non-volatile part/km greater than 23 nm size to 6.0x10₁₁ as determined by the PMP procedure that uses a heated evaporation tube to remove semi-volatile material. Measurement artifacts associated with the evaporation tube technique prevents reliable extension of the method to a lower size range. Catalytic stripper (CS) technology removes possible sources of these artifacts by effectively removing all hydrocarbons and sulfuric acid in the gas phase in order to avoid any chemical reactions or re-nucleation that may cause measurement complications. The performance of a miniature CS was evaluated and experimental results showed solid particle penetration was 50% at 10.5 nm. The sulfate storage capacity integrated into the CS enabled it to chemically remove sulfuric acid vapor rather than rely on dilution to prevent nucleation. Sulfuric acid re-nucleation was not observed until the challenge concentration was higher than 10 mg/m₃.
Technical Paper
2013-04-08
Johann C. Wurzenberger, Roman Heinzle, Maxime-Vianney Deregnaucourt, Tomaz Katrasnik
Engine simulation can be performed using model approaches of different depths in capturing physical effects. The present paper presents a comprehensive comparison study on seven different engine models. The models range from transient 1D cycle resolved approaches to steady-state non-dimensional maps. The models are discussed in the light of key features, amount and kind of required input data, model calibration effort and predictability and application areas. The computational performance of the different models and their capabilities to capture different transient effects is investigated together with a vehicle model under real-life driving conditions. In the trade-off field of model predictability and computational performance an innovative approach on crank-angle resolved cylinder modeling turned out to be most beneficial. It covers a high level of physical based approaches needed in early development phases and it runs in real-time as needed to support calibration in late development phases.
Technical Paper
2013-04-08
Leonidas Ntziachristos, Stavros Amanatidis, Zissis Samaras, Barouch Giechaskiel, Alexander Bergmann
The Particle Measurement Programme (PMP) developed an exhaust particle number measurement protocol that has been adopted by current light duty vehicle emission regulations in Europe. This includes thermal treatment of the exhaust aerosol to isolate solid particles only and a number counting device with a lower cutpoint of 23 nm to avoid measurement of smaller particles that may affect the repeatability of the measurement. In this paper, we examine a potential alternative to the PMP system, where the thermal treatment is replaced by a catalytic stripper (CS). This offers oxidation and not just evaporation of the volatile components. Alternative sampling systems, either fulfilling the PMP recommendations or utilizing a CS, have been explored in terms of their volatile particle removal efficiency. Tests have been conducted on diesel exhaust, diesel equipped with DPF and gasoline direct injection emissions. The results showed that the CS offers similar performance characteristics to the PMP when tested on diesel exhaust.
Technical Paper
2013-04-08
Michael Howlett, Bernhard Enzi, Georg von Falck, Wolfgang Schoeffmann, Reinhold Haslinger, Mario Brunner
The need for significant reduction of fuel consumption and CO₂ emissions has become the major driver for development of new vehicle powertrains today. For the medium term, the majority of new vehicles will retain an internal combustion engine (ICE) in some form. The ICE may be the sole prime mover, part of a hybrid powertrain or even a range extender; in every case potential still exists for improvement in mechanical efficiency of the engine itself, through reduction of friction and of parasitic losses for auxiliary components. A comprehensive approach to mechanical efficiency starts with an analysis of the main contributions to engine friction, based on a measurement database of a wide range of production engines. Thus the areas with the highest potential for improvement are identified. For each area, different measures for friction reduction may be applicable with differing benefits. The proposed measures may be cost intensive, such as the addition of low friction coatings, or variable-capacity pumps, whereas others such as the optimization of cylinder bore distortion or coolant pressure drop by design measures have zero add-on cost.
Technical Paper
2013-04-08
Christoph Breitfuss, Wolfgang Sinz, Florian Feist, Gregor Gstrein, Bernhard Lichtenegger, Christoph Knauder, Christian Ellersdorfer, Joerg Moser, Hermann Steffan, Michael Stadler, Peter Gollob, Volker Hennige
This study deals with the experimental investigation of the mechanical properties of a lithium-ion pouch cell and its modelling in an explicit finite element simulation code. One can distinguish between ‘macroscopic’ and ‘microscopic’ modelling approaches. In the ‘macroscopic’ approach, one material model approximates the behaviour of multiple inner cell layers. In the ‘microscopic’ approach, which is used in the present study, all layers and their interactions are modelled separately. The cell under study is a pouch-type lithium-ion cell with a liquid electrolyte. With its cell chemistry, design, size and capacity it is usable for automotive applications and can be assembled into traction batteries. One cell sample was fully discharged and disassembled, and its components (anode, cathode, separator and pouch) were examined and measured by electron microscopy. Components were also tensile tested. In this way, each component was fully characterised with respect to the properties needed for explicit finite element models.
Technical Paper
2013-04-08
Oldrich Vitek, Jan Macek, Christoph Poetsch, Reinhard Tatschl
The presented paper deals with a methodology to model cycle-to-cycle variations (CCV) in 0-D/1-D simulation tools. This is achieved by introducing perturbations of combustion model parameters. To enable that, crank angle resolved data of individual cycles (pressure traces) have to be available for a reasonable number of engine cycles. Either experimental data or 3-D CFD results can be applied. In the presented work, experimental data of a single-cylinder research engine were considered while predicted LES 3-D CFD results will be tested in the future. Different engine operating points were selected - both stable ones (low CCV) and unstable ones (high CCV). The proposed methodology consists of two major steps. First, individual cycle data have to be matched with the 0-D/1-D model, i.e., combustion model parameters are varied to achieve the best possible match of pressure traces - an automated optimization approach is applied to achieve that. Second, the combustion model parameters (obtained in previous step) are statistically evaluated to obtain PDFs and cross-correlations.
Technical Paper
2013-03-25
Gerhard Kokalj, Ruangrit Ekachaiworasin
The automotive industry is racing to introduce some degree of hybridization into their product ranges. Since the term "hybrid vehicle" can cover a wide range of differing technologies and drivetrain topologies, this has led to a plethora of vehicles that call them "hybrid." This poses an interesting challenge for marketers to differentiate these vehicles from the incumbents. However, it is not just the marketers who are faced with challenges, the developers of such hybrid drivetrains are faced with a rise in technical complexity due to the wide range of operating modes hybridization introduces. As propulsive torque is being generated in more than one place in a hybrid vehicle, the transitions from conventional drive to electrically supported drive bring with them complex aspects of multi-dimensional system control. The challenge is to be able to implement hybrid technology in an existing drivetrain, while adapting the existing components as required. The functional variability of hybrid technology, however, permits a range of possible implementations and the control calibration tasks themselves need to be well structured concerning hand-over, traceability and robustness.
Technical Paper
2012-10-23
Christian Hubmann, Wolfgang Schoeffmann, Hubert Friedl, Bernhard Graf
Beside the automotive industry, where 2-cylinder inline engines are catching attention again, twin-cylinder configurations are quite usual in the small engine world. From stationary engines and range-extender use to small motorcycles up to big cruisers and K-Cars this engine architecture is used in many types of applications. Because of very good overall packaging, performance characteristics and not least the possibility of parts-commonality with 4-cylinder engines nearly every motorcycle manufacturer provides an inline twin in its model range. Especially for motorcycle applications where generally the engine is a rigid member of the frame and vibrations can be transferred directly to the rider an appropriate balancing system is required. A 360° parallel twin engine does generate both: free 1st order mass forces and free 2nd order mass forces. 1st order mass forces can be compensated by a balancer shaft which is the most common, the implementation of a reciprocating balancer weight would eliminate both but has certain drawbacks like complexity, friction and additional excitations.
Technical Paper
2012-06-13
Josef Girstmair, Philippe Albertini, Klaus Meitz, Sigrid Klinger, Hans H. Priebsch, Franz Markus Reich
The new generation of automatic transmissions is characterized by a compact and highly efficient design. By the use of a higher overall gear ratio and lightweight components combined with optimal gear set concepts it is possible to improve significantly fuel consumption and driving dynamics. Precise and efficient real time models of the whole power train including models for complex subsystems like the automatic transmission are needed to combine real hardware with virtual models on XiL test rigs. Thereby it's possible to achieve a more efficient product development process optimized towards low development costs by less needed prototypes and shorter development times by pushing front loading in the process. In this paper a new real time model for automatic transmissions including approved models for the torque converter, the lock-up clutch and the torsional damper are introduced. At the current development stage the model can be used for comfort analysis and drivability assessment. Thereby various operating conditions including motored engine and an open, slipping or locked clutch condition can be simulated.
Technical Paper
2012-06-13
Guenter Offner, Norbert Lorenz, Oliver Knaus
The reduction of acoustic excitation due to piston slap as well as friction loss power and seizure are main issues when simulating the oil film lubricated piston - cylinder contacts of internal combustion engines. For a correct representation of the contact conditions between a piston skirt and a cylinder liner surface both the dynamics of the contacting flexible bodies, the shape of the contacting surfaces, the amount of available oil and the properties of the lubricant itself play important roles. Besides an appropriate representation of the hydrodynamic load carrying capacity using an averaged Reynolds equation with laminar flow conditions, the simulation has to use an appropriate asperity model to consider the mixed lubrication condition. The lubricant properties are in particular influenced by its thermal conditions. In this work a thermo-elastic-hydrodynamic contact model is presented by the averaged Reynolds equation considering local and time variable dynamic viscosity in a mixed lubrication regime.
Technical Paper
2012-06-13
Alois Sontacchi, Robert Holdrich, Josef Girstmair, Hannes Allmaier, Stefan Bikker, Alfred Rust
In the past the exterior and interior noise level of vehicles has been largely reduced to follow stricter legislation and due to the demand of the customers. As a consequence, the noise quality and no longer the noise level inside the vehicle plays a crucial role. For an economic development of new powertrains it is important to assess noise quality already in early development stages by the use of simulation. Recent progress in NVH simulation methods of powertrain and vehicle in time and frequency domain provides the basis to pre-calculated sound pressure signals at arbitrary positions in the car interior. Advanced simulation tools for elastic multi-body simulation and novel strategies to measure acoustical transfer paths are combined to achieve this goal. In order to evaluate the obtained sound impression a roughness prediction model has been developed. The proposed roughness model is a continuation of the model published by Hoeldrich and Pflueger. Within the model simultaneous as well as temporal masking effects are considered.
Technical Paper
2012-06-13
Stephan Brandl, Bernhard Graf, Alfred Rust
Driven by worldwide climate change, governments are introducing more stringent emission regulations with particular focus on fuel saving for CO₂ emission reduction. Downsizing and weight reduction are two of the main drivers to achieve these demanding regulations. Both aspects however might have a strong negative effect on the overall vehicle NVH behavior. Weight reduction directly influences NVH due to reduction of absorption and damping material and due to light-weight design affecting the dynamic responses of powertrain and vehicle structures. Engine downsizing however has multiple negative effects on NVH. Beside higher vibrations and speed irregularities due to lower cylinder numbers and displacements also reduction of sound quality is a critical topic that will be handled within this publication. The first part of this publication will focus on excitation of engines with different number of cylinders, an alternative mounting solution for 3-cylinder engines and an overview on the changes of sound quality for downsized engines.
Technical Paper
2012-04-16
Mirko Baratta, Nicola Rapetto, Ezio Spessa, Alois Fuerhapter, Harald Philipp
This paper presents the results of part of the research activity carried out by the Politecnico di Torino and AVL List GmbH as part of the European Community InGAS Collaborative Project. The work was aimed at developing a combustion system for a mono-fuel turbocharged CNG engine, with specific focus on performance, fuel economy and emissions. A numerical and experimental analysis of the jet development and mixture formation in an optically accessible, single cylinder engine is presented in the paper. The experimental investigations were performed at the AVL laboratories by means of the planar laser-induced fluorescence technique, and revealed a cycle-to-cycle jet shape variability that depended, amongst others, on the injector characteristics and in-cylinder backpressure. Moreover, the mixing mechanism had to be optimized over a wide range of operating conditions, under both stratified lean and homogeneous stoichiometric modes. For this reason the experimental activity was supported by the numerical simulations of CNG injection, jet formation and air-fuel mixing, in order to have a deep insight into the injected gas behavior.
Technical Paper
2012-04-16
Harald Altenstrasser, Yoshihisa Kato, Nikolaus Keuth, Thomas Winsel
A calibration and validation workflow will be presented in this paper, which utilizes common static global models for fuel consumption, NOx and soot. Due to the applicability for warm-up tests, e. g. New European Driving Cycle (NEDC), the models need to predict the temperature influence and will be fitted with measuring data from a conditioned engine test bed. The applied model structure - consisting of a number of global data-based sub-models - is configured especially for the requirements of multi-injection strategies of common rail systems. Additionally common global models for several constant coolant water temperature levels are generated and the workflow tool supports the combination and segmentation of global nominal map with temperature correction maps for seamless and direct ECU setting. To globally validate the ECU calibration with respect to emission limits, fuel consumption and special regard to transient operation phases, the complete model chain will be stimulated with NEDC warm up tests.
Technical Paper
2012-04-16
Johann C. Wurzenberger, Ivo Prah, Primoz Tominc, Tomaz Katrasnik
This paper presents a comparison of a hybrid and a conventional powertrain using physical based simulation models on the system engineering level. The system engineering model comprises mechanistic sub-models of the internal combustion engine including exhaust aftertreatment devices, electric components, mechanical drivetrain, thermoregulation system and the corresponding controllers. Essential sub-models are discussed in detail and their interaction on the system level is pointed out. Special attention is paid to compile a real-time capable model by combining mean value air path and drivetrain models with a crank-angle resolved cylinder description and quasi-steady state considerations applied in electrical and cooling networks. A turbocharged gasoline direct injection engine is modeled and calibrated based on steady-state measurements. The conversion performance of a three way catalyst is compared to light-off measurements. A hybrid electric vehicle model combines the turbocharged engine with the electric and driveline components of the Toyota Prius hybrid vehicle.
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