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Viewing 1 to 30 of 105
2010-09-28
Technical Paper
2010-32-0019
Roland Oswald, Andreas Ebner, Roland Kirchberger
The Institute of Internal Combustion Engines and Thermodynamics at Graz University of Technology has developed a low-pressure (5 bar) direct injection (LPDI) combustion system for 50 cm₃ two-stroke engines during the last years. The 50 cm₃ two-stroke engine is a specific European engine class. Worldwide the 125 cm₃ class is more important. In order to investigate the potential of higher displacement engines equipped with the LPDI combustion process, a demonstrator engine with 250 cm₃ has been developed. The results of this demonstrator from the engine test bench and from the chassis dynamometer are discussed to show the potential of this two-stroke technology. In order to ease the interpretation, the results of a homogenously scavenged two-stroke engine and of a naturally aspirated four-stroke engine serve as reference. The results show that the LPDI technology is a real alternative to expensive four-stroke engines.
2010-09-28
Technical Paper
2010-32-0017
Oliver Schoegl, Stephan Schmidt, Martin Abart, Christian Zinner, Roland Kirchberger, Mathias Fitl, Karl Glinsner, Stefan Leiber
The development process of 2-stroke engines is characterized by limited CFD investigations in combination with long-term development phases on the test bench with high prototype costs. To reduce the costs and to realize shorter development time together with a higher prediction quality of the engine potential, a higher implementation level of 1D and 3D simulation tools into the development process is necessary. This publication outlines the 1D simulation methods in the layout phase of GDI combustion processes of 2-stroke engine categories. By means of conceptual investigations, the demands, the potential and the limits of 1D CFD simulation methodology are defined. Using a comparison between 1D and 3D or 1D/3D coupled simulation methods the limits of solely 1D simulation are shown. For advanced simulation tasks with a higher demand for prediction quality, the entire engine is simulated in 1D, whereas special parts of the engine design are simulated in a 3D model.
2010-09-28
Technical Paper
2010-32-0014
Dalibor Jajcevic, Raimund Almbauer, Stephan Schmidt, Karl Glinsner, Matthias Fitl
The advantages of 2-stroke engines, high power and low weight, are in conflict with their disadvantages, high emissions and bad fuel economy. As these disadvantages are caused by the scavenging process, a reason for the problem can be analyzed by using three dimensional computational fluid dynamics simulation (3D CFD simulation). The scavenging losses can be dramatically reduced with a high pressure fuel injection strategy. The purpose of this strategy is to prevent a fuel concentration in the incoming charge and to reduce the fuel concentration inside the exhaust system. These advantages can only be successfully exploited with the application of an optimal injection strategy. This paper covers a spray study for a gasoline direct injection (GDI) high performance 2-stroke engine using the commercial CFD Code Fluent.
2010-09-28
Journal Article
2010-32-0015
Dalibor Jajcevic, Raimund Almbauer, Stephan Schmidt, Karl Glinsner, Matthias Fitl
CFD has been widely used to predict the flow behavior inside 2-stroke engines over the past twenty years. Usually a mass flow profile or a simple 0D model is used for the inlet boundary condition, which replaces the complete intake geometry, such as reed valve, throttle, and air box geometries. For a CFD simulation which takes into account the exact reed valve geometry, a simulation of all above mentioned domains is required, as these domains are coupled together and thus interact. As the high speed of the engine affects the opening dynamic and closure of the reed valve, the transient data from the crank case volume and the section upstream the reed valve have an important influence on the reed petal dynamic and therewith on the sucked fresh air mass of the engine. This paper covers a methodology for the transient CFD simulation of the reed petals of a 2-stroke engine by using a 2D model.
2010-09-28
Technical Paper
2010-32-0035
Dalibor Jajcevic, Matthias Fitl, Stephan Schmidt, Karl Glinsner, Raimund Almbauer
The exhaust system design has an important influence on the charge mass and the composition of the charge inside the cylinder, due to its gas dynamic behavior. Therefore the exhaust system determines the characteristics of the indicated mean effective pressure as well. The knowledge of the heat transfer and the post-combustion process of fuel losses inside the exhaust system are important for the thermodynamic analysis of the working process. However, the simulation of the heat transfer over the exhaust pipe wall is time consuming, due to the demand for a transient simulation of many revolutions until a cyclic steady condition is reached. Therefore, the exhaust pipe wall temperature is set to constant in the conventional CFD simulation of 2-stroke engines. This paper covers the discussion of a simulation strategy for the exhaust system of a 2-cylinder 2-stroke engine until cyclic steady condition including the heat transfer over the exhaust pipe wall.
2010-09-28
Technical Paper
2010-32-0030
Martin Abart, Stephan Schmidt, Oliver Schoegl, Alexander Trattner, Roland Kirchberger, Helmut Eichlseder, Dalibor Jajcevic
This publication covers investigations on different 3D CFD models for the description of the spray wall and droplet-fluid interaction and the influence of these models on the mixture formation calculation results. Basic experimental investigations in a spray chamber and a flow tunnel as well as the corresponding 3D CFD simulation were conducted in order to clarify the prediction quality of the physical phenomena of spray-wall and spray-fluid interaction by the simulation. Influencing parameters such as the piston top temperature, piston bowl geometry, soot deposits on the piston top as well as flow velocity are investigated. This paper provides a direct link between the underlying simulation models of the mixture formation and actual real world combustion system development processes - underlining the importance of a close interaction of the model calibration and the development process.
2010-10-25
Technical Paper
2010-01-2086
Peter Grabner, Helmut Eichlseder, Gregor Eckhard
This paper presents an analysis of the potential of E85 (a mixture of 85 % (bio)ethanol and 15 % gasoline) as a fuel for spark-ignition (SI) direct-injection internal combustion engines. This involves investigation of not only application to downsizing concepts with high specific power but also behavior relating to emissions and efficiency at both part and full load. Measurements while running on gasoline were used for comparison purposes. The first stage involved analysis using 1D simulation of two different downsizing concepts with regard to turbocharging potential and performance. Following this, various influential parameters such as injector position, injection pressure, compression ratio, degree of turbocharging etc. were investigated on a single cylinder research engine. In the case of high pressure direct injection, particulate emissions also play an important role, so particulate count and particulate size distribution were also studied in detail.
2010-10-10
Technical Paper
2010-01-1712
Daniel Wallner, Stefan Bernsteiner, Wolfgang Hirschberg, Alexander Rabofsky
This paper deals with the analysis of a complete axle of a passenger car, which shows brake squeal in test runs. The complete brake system including the parts of the corner is studied with two different Finite Element Analysis programs and their brake squeal calculation algorithms. Thereby significant differences between the results of the two simulations and also the experiments are observed. The used element type and the chosen discretisation level influence largely the simulated contact and thereby the overall results. In order to explain these outcomes, the force distribution and the force vectors between disc and pad are analysed. On the one hand tetrahedral elements cause stiffening of the parts and hence of the contact. On the other hand the effort to create hexahedral elements in daily meshing practice is often omitted due to cost reasons. This trend is enforced by the statement of software vendors.
2010-04-12
Technical Paper
2010-01-0649
Martin Benedikt, Hannes Stippel, Daniel Watzenig
In the automotive industry well-established different simulation tools targeting different needs are used to mirror the physical behavior of domain specific components. To estimate the overall system behavior coupling of these components is necessary. As systems become more complex, simulation time increases rapidly by using traditional coupling approaches. Reducing simulation time by still maintaining accuracy is a challenging task. Thus, a coupling methodology for co-simulation using adaptive macro step size control is proposed. Convergence considerations of the used algorithms and scheduling of domain specific components are also addressed. Finally, the proposed adaptive coupling methodology is examined by means of a cross-domain co-simulation example describing a hybrid electric vehicle. Considerable advantages in terms of simulation time reduction are presented and the trade-off between simulation time and accuracy is depicted.
2004-03-08
Technical Paper
2004-01-0341
Hermann Steffan, Andreas Moser
Due to the increasing number of minivans and sport utility vehicles, rollovers have become more significant. As a result, various accident reconstruction programs have been developed to address this issue. To reconstruct rollover crashes, various requirements have to be fulfilled. These consist of: providing a simple method that is able to model three dimensional environments that often play a major role in rollovers. including suspension, tire and collision models must be provided. This is particularily important in the rollover initiation phase. including proper vehicle geometry and contact stiffness must be available. These are important for simulation of body contacts that affect the vehicle motion. This study focuses on one program, PC-CRASH. This program was developed to allow simulations of vehicle 3-dimensional movements before, during and after the impact. The study also discusses the physical background of the models, their capabilities as well as their limitations.
2014-04-01
Technical Paper
2014-01-1005
Helmut Brunner, Mario Hirz
Abstract Increasing urbanization, the growing degree of motorization and traffic performance in urban areas and environmental aspects like greenhouse gas emissions (GHG) are the motivation for a detailed analysis of personal individual mobility in urban areas, which is presented in this study. In the first step, the publication examines a study of market potential of new small and lightweight vehicle concepts. A mobility inquiry conducted in a mid-sized European city enables an estimation of the potential user groups for alternative vehicle concepts for individual urban traffic. In a second step, the CO2 reduction potential of urban car concepts is simulated for a generic vehicle fleet. This fleet consists of conventional vehicles of various classes (subcompact, compact, mid-sized …) as well as new lightweight urban car concepts. A novel vehicle concept for urban transportation will be presented as well.
2013-10-15
Technical Paper
2013-32-9124
Hermann Edtmayer, Alexander Trattner, Stephan Schmidt, Roland Kirchberger, Jakob Trentini, Johann Weiglhofer
This paper introduces a research project on a spark ignition engine used in non-road applications. The aim is to illustrate the present situation as basis for comparison and to identify possible improvement potential in terms of performance, efficiency or exhaust and noise emissions. The study is carried out in two steps. First a standard walk-behind lawn mower is equipped with measuring instrumentation for recording the cutting forces and the engine variables during real world operation. The tests are carried out on three different lawn types and two different blade types are investigated. Consequently, in a second step the engine is analysed on the engine test bench in stationary and transient operating mode. A complete engine mapping is done regarding all relevant variables. Additionally to the outdoor tests, fuel consumption and engine out emissions are measured on the engine dynamometer. The recorded data enables a detailed analysis of the engine behaviour.
2013-10-15
Technical Paper
2013-32-9130
Cecile Favre, John May, Dirk Bosteels, Jurgen Tromayer, Gerd Neumann
To get an overview of the emission situation in the field of small non-road mobile machinery powered by various types of SI engines, the Association for Emissions Control by Catalyst (AECC), together with the Institute for Internal Combustion Engines and Thermodynamics (IVT) of Graz University of Technology, conducted a customized test program. The main goal for this campaign was to derive information regarding the emissions of regulated gaseous components (following European Directive 97/68/EC) as well as particulate matter. With regard to the big variety of different engines that are available on the European and North-American market, the most representative ones had to be chosen. This resulted in a pool of test devices to cover different engine working principles (2-Stroke and 4-Stroke), technological standards (low-cost and professional tools) and different emissions control strategies (advanced combustion and exhaust gas aftertreatment).
2011-05-17
Technical Paper
2011-01-1576
Stefan Bernsteiner, Daniel Wallner
Experimental researches on brake squeal have been performed since many years in order to get an insight into friction-excited vibrations and squeal triggering mechanisms. There are many different possibilities to analyse brake squeal. The different operating deflection shapes can be detected using e.g. laser vibrometer systems or acceleration sensors. Piezoelectric load cells can be used for the measurement of the normal contact force of the brake pad. The presented test setup measures not only the mean value of the friction force between brake pad and disc at a certain brake pressure, but also the superposed vibration of this force, which only occurs during a squeal event. Therefore the guide pins of the brake caliper are replaced by modified ones. The brake pads are held in position by these pins and the resulting force of the brake torque, hence the friction force, acts on these pins. The shape of the pins is optimized for measuring these forces.
2011-04-12
Technical Paper
2011-01-1439
Christoph Poetsch, Herwig Ofner, Eberhard Schutting
The paper describes a universally structured simulation platform which is used for the analysis and prediction of combustion in compression ignition (CI) engines. The models are on a zero-dimensional crank angle resolved basis as commonly used for engine cycle simulations. This platform represents a kind of thermodynamic framework which can be linked to single and multi zone combustion models. It is mainly used as work environment for the development and testing of new models which thereafter are implemented to other codes. One recent development task focused on a multi zone combustion model which corresponds to the approach of Hiroyasu. This model was taken from literature, extended with additional features described in this paper, and implemented into the thermodynamic simulation platform.
2010-09-28
Technical Paper
2010-32-0129
Andreas Ebner, Franz Winkler, Martin Abart, Raphael Luz, Roland Kirchberger, Stephan Schmidt, Helmut Eichlseder
The future exhaust emission legislation limits and the procedures for running the test cycles will have an important influence on future range extender concepts. Due to the special steady state operation strategy of the range extender engines, it is possible to create a simple methodology for comparing engine test bench emissions with the emission limits of exhaust gas legislations. Therefore the energy demand of a predefined vehicle was simulated with PHEM, a longitudinal dynamic simulation tool. According to that, the influence of different exhaust gas after treatment systems and preheating options on the tolerated raw emission concentration will be analyzed. With this information, a few chosen range extender engine concepts will be compared concerning their suitability for future exhaust emission legislations. The selection of the range extender concepts was carried out with the methotology of a value benefit analysis.
2010-09-28
Technical Paper
2010-32-0094
Stephan Schmidt, Martin Joyce, Jonathan Wall, Alexander Trattner, Roland Kirchberger, Helmut Eichlseder
In the course of the last few years a continuous increase of the injection pressure level of gasoline direct injection systems appeared. Today's systems use an injection pressure up to 200bar and the trend shows a further increase for the future. Although several benefits go along with the increased injection pressure, the disadvantages such as higher system costs and higher energy demand lead to the question of the lowest acceptable injection pressure level for low cost GDI combustion systems. Lowering injection pressure and costs could enable the technological upgrading from MPFI to GDI in smaller engine segments, which would lead to a reduction of CO2 emission. This publication covers the investigation of a low pressure GDI system (LPDI) with focus on small and low cost GDI engines. The influence of the injection pressure on the fuel consumption and emission behavior was investigated using a 1.4l series production engine.
2000-03-06
Technical Paper
2000-01-0847
Andreas Moser, Heinz Hoschopf, Hermann Steffan, Gustav Kasanicky
The pedestrian model in PC-Crash is based on a multi-body system, where several bodies are interconnected by joints. Each of these bodies can have different properties to represent the different parts of the human body. The joint properties can be specified independently as well. The theoretical background of the pedestrian model has been introduced in SAE 1999-01-0445 and the model shows to give a good correlation of the gross movement of the pedestrian compared to crash test data. As there are many parameters, which can and have to be specified for the pedestrian model as input parameters, an in depth validation of the different parameters has to be done to validate this model. This paper describes in detail the validation process for the pedestrian model. A significant number of crash tests (approx. 30) was used as a basis to compare the results of the simulations and the real movement of the test subjects.
2011-11-08
Technical Paper
2011-32-0592
Hans-Jürgen Schacht, Roland Kirchberger, Franz Winkler, Stephan P. Schmidt
Nowadays, politicians are forced by air pollution prevention to demand zero emission vehicles (ZEV) in the form of pure electric vehicles. The poor capacity to weight factor of actual batteries compared to any kind of liquid or gaseous hydro-carbon fuel is the main reason for the retarded implementation of ZEV. Solutions offered by automobile manufacturers are mild to full hybrid powertrains based on the well established ICE platform. The difficulty of those approaches of electrification is to compete with the performance and benefit costumers expect from standard automobiles. Pure electric vehicles are rare and often disappointing regarding range and/or performance. Additionally the costs for such vehicles, which are mainly driven by the battery prices, are comparatively high, impeding their market entrance and acceptance. Low price electric city scooters are actually offered as pure electric vehicles in a wide variety of different models.
2011-11-08
Journal Article
2011-32-0587
Jürgen Tromayer, Gerd Neumann, Roland Kirchberger
Usually the power output of 50 cm₃ two wheelers is higher than necessary to reach the maximum permitted vehicle speed, making engine power restriction necessary. This publication deals with different power restriction strategies for four-stroke engines and their effect on exhaust emissions. Alternative power limitation strategies like EGR and leaning were investigated and compared with the common method of spark advance reduction to show the optimization potential for this certain engine operation conditions. From these tests, a substantial set of data showing the pros and cons in terms of emissions, combustion stability and fuel economy could be derived for each speed limiting technique.
2011-11-08
Technical Paper
2011-32-0585
C. Zinner, M. Abart, O. Schögl, St. Schmidt, S. Leiber, T. Schabetsberger
In this study, investigations on charging strategies for motorcycle applications have been performed on the basis of modern charging concepts. These investigations had been driven by the goal of CO₂ reduction and optimization of packaging size, while maintaining the extraordinary dynamic response behavior of modern motorcycle engines. Based on experimental investigations of the boundary conditions and restrictions of motorcycle applications in contrast to automotive applications, intense experimental test bench and on the road investigations of the stationary and transient behavior of charging strategies have been performed. These investigations covered automotive state-of-the-art charged engines as well as charged motorcycle applications. With these results, simulations of the air path for stationary and transient operation were used in order to evaluate the potential of several charging strategies for motorcycle applications.
2011-11-08
Technical Paper
2011-32-0572
Cécile Favre, John May, Dirk Bosteels, Jürgen Tromayer, Gerd Neumann, Roland Kirchberger, Helmut Eichlseder
The European emission legislation for two-wheeler vehicles driven by engines of ≤ 50 cm₃ is continuously developing. One of the most important issues in the near future will be the finalization of the European Commission's proposals for future steps in the emissions regulations as well as the verification of the impacts of current standards on the market. To have a basis for the discussion about these topics, the Association for Emissions Control by Catalyst (AECC) with the Institute for Internal Combustion Engines and Thermodynamics of Graz University of Technology (IVT) carried out an extensive test program to show the actual emission situation of state-of-the-art mopeds including mass and number of particulate matter as well as unregulated gaseous components. One of the main goals of these tests was to measure exhaust emissions without any modifications to the engines of standard production vehicles available on the European market.
2011-10-04
Technical Paper
2011-36-0132
Andrés Eduardo Rojas Rojas, Haymo Niederkofler, Wolfgang Hirschberg
Volatile oil prices and increased environmental sensitivity together with political concerns have moved the attention of governments, automobile manufacturers and customers to alternative power trains. From the actual point of view the most promising concepts for future passenger cars are based on the conversion of electrical into mechanical energy. In-wheel motors are an interesting concept towards vehicle electrification that provides also high potentials to improve vehicle dynamics and handling. Beside aspects concerning the electric system (e.g. motor type, energy storage, and control strategy), there are also some open questions related with the mechanical design of in-wheel motor driven vehicles that need to be solved before series production.
2011-11-08
Journal Article
2011-32-0596
A. Trattner, P. Pertl, St. P. Schmidt, Takaaki Sato
Energy politics and environmental circumstances demand novel strategies for private transport. Several studies have shown that one of these possibilities can be an electric vehicle with a range extender - REX. Today these REX engines are under way as derivation from modern internal combustion engines. As the need for an optimized usage of energy will further increase in the future, alternative energy converter systems have to be investigated. For DENSO, as supplier of components, it is of strong interest how the basic layout of these concepts could look like. This is necessary in order to be prepared for the specific needs of these concepts in terms of auxiliaries, electric / electronic components as well as for the cabin climate & various control strategies. In these REX-concepts all energies have to be considered. A sophisticated usage of energy inside a REX vehicle is required which leads to the investigation of a combined heat and power usage on-board.
2005-04-11
Technical Paper
2005-01-0108
Andreas Wimmer, Thomas Wallner, Jürgen Ringler, Falk Gerbig
Hydrogen is frequently cited as a future energy carrier. Hydrogen allows a further optimization of internal combustion engines, especially with direct injection. In order to assess various concepts, detailed thermodynamic analyses were carried out. Effects, which can be neglected with conventional fuels (e.g. losses due to injection during compression stroke) are considered. These basics as well as several results from test bed investigations are described within this article. Wall heat losses were found to have a major influence on overall efficiency and are thus investigated in detail, based on local surface temperature measurement. Finally, concepts that allow an increase in engine efficiency and lowest NOx emissions are demonstrated.
2010-06-09
Journal Article
2010-01-1422
Johannes Sebastian Hölzl, Walter Sextro
For many technical applications it is necessary to avoid or to reduce vibrations. Factors benefiting from vibration reduction are for example the durability of the application, which is increased, as well as cost expenses and the level of noise, which are both decreased. Rough, bolted interfaces are common in most machines and can be used as damping devices with some effort. Perhaps in future such contact surfaces could be used as damping devices at the interfaces of an automotive engine or exhaust system. Nevertheless it is difficult to predict the effect of a change in contact interface parameters on the dynamic behavior of the entire mechanical system. Therefore a method for calculating the steady state behavior of elastic multi-body systems was developed. The basis of this method is a finite element model of each contacting unit. On each model a modal reduction is applied in order to reduce the degrees of freedom.
2012-10-23
Technical Paper
2012-32-0083
Hans-Juergen Schacht, Oliver Schoegl, Niko Bretterklieber, Roland Kirchberger, Stephan Schmidt
Electric driving is generally limited to short distances in an emission sensible urban environment. In the present situation with high cost electric storage and long charging duration hybridization is the key to enable electric driving. In comparison to the passenger car segment, where numerous manufacturers are already producing and offering different hybrid configurations for their premium class models, the two wheeler sector is not yet affected by this trend. The main reason for the retarded implementation of this new hybrid technology is its high system costs, as they cannot be covered by a reasonable product price. Especially for the two wheeler class L1e, with a maximum speed of 45 km/h and an engine displacement of less than 50 cm₃, the cost factor is highly important and decisive for its market acceptance, because the majority of vehicles are still low-cost products equipped with simple carbureted 2-stroke engines.
2017-01-10
Technical Paper
2017-26-0326
Michael Wohlthan, Gerhard Pirker, Igor Sauperl, Andreas Wimmer, Wolfram Rossegger, Norbert Buch
Abstract Experimental investigations on engine test beds represent a significant cost in engine development. To reduce development time and related costs, it is necessary to check the quality of measurements automatically whenever possible directly on the test bed to allow early detection of faults. A fault diagnosis system should provide information about the presence, cause and magnitude of an inconsistency in measurement. The main challenge in developing such a system is to detect the fault quickly and reliably. However, only faults that have actually occurred should be detected because the user will only adopt a system that provides accurate results. This paper presents a methodology for automated fault diagnosis at engine test beds, starting with an explanation of the general procedure. Next, the methods applied for fault detection are introduced.
2015-11-17
Technical Paper
2015-32-0832
Franz Winkler, Roland Oswald, Oliver Schögl, Andrea Abis, Stefan Krimplstatter, Roland Kirchberger
In consideration of the fact that in extreme Enduro competitions two-stroke motorcycles are still dominating, the Institute of Internal Combustion Engines and Thermodynamics, Graz University of Technology, with a long tradition in two-stroke technology, has developed a new 300 cm3 two-stroke motorcycle engine. The 2-stroke LPDI (Low Pressure Direct Injection) technology was originally developed for the 50 cm3 Scooter and moped market in Europe. In 50 cm3 applications the LPDI technology fulfils the EURO 4 emission standard (2017) [1]. In a next step the LPDI technology was applied to a 250 cm3 Enduro engine demonstrator vehicle. Based on the results of the demonstrator, a complete new high performance 300 cm3 engine was developed. The development of this new engine will be described in this publication. Some interesting aspects of the layout with 3D-CFD methods and also 1D-CFD simulation to optimize the exhaust system by DoE methods are discussed in the paper.
2015-11-17
Technical Paper
2015-32-0809
Patrick Pertl, Alexander Trattner, Reinhard Stelzl, Michael Lang, Stephan Schmidt, Roland Kirchberger
The enhancement of efficiency will play a more and more important role in the development of future (small) internal combustion engines. In recent years, the Atkinson cycle, realized over the crank drive, has attracted increasing attention. Several OEMs have been doing investigations on this efficiency-increasing principle with in the whole range from small engines up to automotive ones. In previous publications, the authors stated that an indicated efficiency of up to 48% could be reached with an Atkinson cycle-based engine. However, these studies are based on 1D-CFD simulation. To verify the promising simulation results, a prototype engine, based on the Atkinson principle, was designed and experimentally tested. The aim of the present study is to evaluate and validate the (indicated) engine efficiency gained by experimental tests compared to the predicted simulation results. In order to investigate part load behavior, several valve timing strategies were also developed and tested.
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