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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.
2014-04-01
Technical Paper
2014-01-1103
Sebastian Salbrechter, Markus Krenn, Gerhard Pirker, Andreas Wimmer, Michael Nöst
Abstract Optimization of engine warm-up behavior has traditionally made use of experimental investigations. However, thermal engine models are a more cost-effective alternative and allow evaluation of the fuel saving potential of thermal management measures in different driving cycles. To simulate the thermal behavior of engines in general and engine warm-up in particular, knowledge of heat distribution throughout all engine components is essential. To this end, gas-side heat transfer inside the combustion chamber and in the exhaust port must be modeled as accurately as possible. Up to now, map-based models have been used to simulate heat transfer and fuel consumption; these two values are calculated as a function of engine speed and load. To extend the scope of these models, it is increasingly desirable to calculate gas-side heat transfer and fuel consumption as a function of engine operating parameters in order to evaluate different ECU databases.
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).
2014-04-01
Technical Paper
2014-01-1319
Christof Hepp, Markus Krenn, Josef Wasserbauer, Helmut Eichlseder
Abstract Dual Fuel concepts are of interest from different perspectives: use of available fuel, independence of supplier, emission reduction and energy costs. This article presents the results of experimental work investigating the possible combination and functional effects of gasoline and diesel fuels. The test bed setup for a single cylinder research engine with a displacement of 2 liters allows gasoline to be added by external mixture formation and combustion to be started by diesel pilot injection. The goal is to reduce the engine out pollutant emissions, while keeping the efficiency at a level comparable to a modern diesel engine. The main focus is on reducing soot and nitric oxide emissions. The charge composition of gasoline is homogenous, so the combustion system can also be seen as a partial or fully homogenous combustion concept, depending on the ignition timing and the ignition delay of the diesel fuel.
2014-11-11
Journal Article
2014-32-0009
Alexander Trattner, Helmut Grassberger, Oliver Schoegl, Stephan Schmidt, Roland Kirchberger, Helmut Eichlseder, Armin Kölmel, Stephan Meyer, Tim Gegg
Abstract One of the most significant current discussions worldwide is the anthropogenic climate change accompanying fossil fuel consumption. Sustainable development in all fields of combustion engines is required with the principal objective to enhance efficiency. This certainly concerns the field of hand-held power tools as well. Today, two-stroke SI engines equipped with a carburetor are the most widely used propulsion technology in hand-held power tools like chain saws and grass trimmers. To date, research tended to focus on two-stroke engines with rich mixture setting. In this paper the advantages and challenges of leaner and/or lean operation are discussed. Experimental investigations regarding the influence of equivalence ratio on emissions, fuel consumption and power have been performed. Accompanying 3D-CFD simulations support the experiments in order to gain insight into these complex processes. The investigations concentrate on two different mixture formation processes, i.e.
2014-11-11
Technical Paper
2014-32-0008
Stefan Krimplstätter, Franz Winkler, Roland Oswald, Roland Kirchberger
Abstract The Institute for Internal Combustion Engines and Thermodynamics, Graz University of Technology, has presented several applications of its 2-stroke LPDI (low pressure direct injection) technology in the previous years ([1], [2], [3]). In order to improve the competitiveness of the 2-stroke LPDI technology, an air cooled 50cm3 scooter application has been developed. All previous applications have been liquid cooled. This air cooled application demonstrates the EURO 4 (2017) ability of the technology and shows that the 2S-LPDI technology can also be applied to low cost air-cooled engines. Hence, the complete scooter and moped fleet can be equipped with this technology in order to fulfil both the emission standards and the COP (conformity of production) requirements of Euro 4 emission stage. The paper presents the Euro 4 Scooter results and describes the efficient conversion process of the existing carburetor engine to the LPDI version.
2014-11-11
Technical Paper
2014-32-0102
Patrick Pertl, Philipp Zojer, Michael Lang, Oliver Schoegl, Alexander Trattner, Stephan Schmidt, Roland Kirchberger, Nagesh Mavinahally, Vinayaka Mavinahalli
Abstract The automotive industry has made great efforts in reducing fuel consumption. The efficiency of modern spark ignition (SI) engines has been increased by improving the combustion process and reducing engine losses such as friction, gas exchange and wall heat losses. Nevertheless, further efficiency improvement is indispensable for the reduction of CO2 emissions and the smart usage of available energy. In the previous years the Atkinson Cycle, realized over the crank train and/or valve train, is attracting considerable interest of several OEMs due to the high theoretical efficiency potential. In this publication a crank train-based Atkinson cycle engine is investigated. The researched engine, a 4-stroke 2 cylinder V-engine, basically consists of a special crank train linkage system and a novel Mono-Shaft valve train concept.
2014-04-01
Journal Article
2014-01-1888
Jürgen Fabian, Mario Hirz, Klaus Krischan
Discussions about the optimal technology of propulsion systems for future ground vehicles have been raising over the last few years. Several options include different types of technologies. However, those who are advocating conventional internal combustion engines are faced with the fact that fossil fuels are limited. Others favor hydrogen fuel as the solution for the future, either in combination with combustion engines or as an energy carrier for fuel cells. In any case, the production and storage of hydrogen is an ongoing challenge of numerous research works. Finally, there are battery-electric or hybrid propulsion systems in use, gaining more and more popularity worldwide. Ongoing advances in power electronics help to improve control systems within automotive applications. New developed or designed components enable more efficient system architectures and control.
2014-04-01
Technical Paper
2014-01-1875
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).
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.
2010-09-28
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.
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
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
2010-32-0014
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
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.
2012-10-23
Journal Article
2012-32-0111
Alexander Trattner, Stephan Schmidt, Roland Kirchberger, Helmut Eichlseder, Armin Kölmel, Michael Raffenberg, Tim Gegg
Today mankind is using highly sophisticated tools which contribute to maintain the standard of living. Nevertheless, these tools have to be further improved in the near future in order to protect health and environment as well as to ensure prosperity. Two-stroke engines equipped with a carburettor are the most used propulsion technology in hand-held power tools like chain saws and grass trimmers. The shortage of fossil resources and the necessary reduction of carbon dioxide emissions ask for improved engine efficiency. Concurrently, customers demand for an easy usage with high performance at all operating conditions, e.g. varying ambient temperature and pressure and different fuels. Moreover, world-wide emission limits will be even stricter in future. The improvement of the emission level, fuel consumption and customer benefits, while keeping the present advantages of two-stroke engines, like high specific power and simplicity, are the goals of this research work.
2012-10-23
Journal Article
2012-32-0069
Christian Zinner, Reinhard Stelzl, Stephan Schmidt, Stefan Leiber, Thomas Schabetsberger
The main target for the development of power sport engines is and will be in future the increase of the power-to-weight ratio. However, the reduction of carbon dioxide emissions is getting more and more important as future legislation and increasing customer demands ask for lower fuel consumption. One possible technology for CO₂ reduction which is widely used in automotive applications is downsizing by reducing the engine capacity and increasing the specific power by charging strategies. Focusing on power sport applications, like motorcycles, the automotive downsizing technologies cannot be transferred without major modifications. The essential difference to automotive applications is the extraordinary response behavior of today's motorcycles, as well as the large engine speed spread. Additionally, packaging and cost reasons exclude the direct transfer of highly complex automotive technology, like two-stage charging, cam-phasing, etc., to motorcycle applications.
2012-10-23
Technical Paper
2012-32-0059
Patrick Pertl, Alexander Trattner, Andrea Abis, Stephan Schmidt, Roland Kirchberger, Takaaki Sato
Small combustion engines can be found in various applications in daily use (e.g. as propulsion of boats, scooters, motorbikes, power-tools, mobile power units, etc.) and have predominated these markets for a long time. Today some upcoming competitive technologies in the field of electrification can be observed and have already shown great technical advances. Therefore, small combustion engines have to keep their present advantages while concurrently minimizing their disadvantages in order to remain the predominant technology in the future. Whereas large combustion engines are most efficient thermal engines, small engines still suffer from significantly lower efficiencies caused by a disadvantageous surface to volume ratio. Thus, the enhancement of efficiency will play a key role in the development of future small combustion engines. One promising possibility to improve efficiency is the use of a longer expansion than compression stroke.
2012-10-23
Technical Paper
2012-32-0048
Reinhard Stelzl, Roland Kirchberger, Stephan Schmidt, Michael Dopona, Wolfgang Wukisiewitsch, Nigel Foxhall
Aircraft engines in the (ELA1) category, with a maximum power of up to 100kW, are characterized by a verified state of the art technology. New developments of engine technologies and control methods are very slowly being introduced into this engine segment. This trend is based on the fact that new technologies implemented in aircraft engines must be thoroughly certified and validated in a very complex and documented procedure. For this reason, most of the engines in this class are equipped with a carburetor as an air/fuel mixture preparation system. Moreover, naturally aspirated spark ignited engines are widely used in the aircraft category, with a take-off weight of up to 1000kg.
2006-04-03
Technical Paper
2006-01-0448
Dieter Messner, Andreas Wimmer, Udo Gerke, Falk Gerbig
Hydrogen is seen as a promising energy carrier for a future mobility scenario. Applied as fuel in IC engines with internal mixture formation, hydrogen opens up new vistas for the layout of the combustion system. The 3D CFD simulation of internal mixture formation as well as combustion helps to understand the complex in-cylinder processes and provides a powerful tool to optimize the engine's working cycle. The performance of standard simulation models for mixture formation as well as the performance of a user-defined combustion model applied in a commercial CFD-code is discussed within this article. The 3D CFD simulations are validated with measurements obtained from a thermodynamic and from an optical research engine respectively.
2006-11-13
Technical Paper
2006-32-0091
Matjaž Korman, Mario Hirz, Roland Kirchberger, Franz Winkler, Alfred Reck, Friedrich - Wilhelm Kaiser
State of the art technologies of 2 and 4 stroke engines have to fulfill severe future exhaust emission regulations, with special focus on the aspects of rising performance and low cost manufacturing, leading to an important challenge for the future. In special fields of applications (e.g. mopeds, hand held or off-road equipment) mainly engines with simple mixture preparation systems, partially without exhaust gas after treatment are used. The comparison of 2 and 4 stroke concepts equipped with different exhaust gas after treatment systems provides a decision support for applications in a broad field of small capacity engine classes.
2004-01-01
Technical Paper
2004-01-2105
Mario Hirz, Roland Kirchberger, Michael Rumpl
An efficient and economic method to increase the performance of four stroke engines can be accomplished by utilizing the crankcase supercharging method. The lubrication of the movable parts in the crankcase by mixing the intake air with lubricant leads to a high oil consumption and disadvantages in the emission characteristics. This paper describes parts of a research project with the goal to develop a supercharged four–stroke engine with a closed loop lubrication system for the crank train and the cylinder head. The thermodynamic layout and the development of an oil separating system have been carried out with the help of simulation tools and development work on a flow test bench.
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.
2003-06-23
Technical Paper
2003-01-2267
Helmut Eichlseder, Thomas Wallner, Raymond Freymann, Jürgen Ringler
Focus is pointed on the highly favorable physical properties of hydrogen (H2) with regard to its combustion characteristics in internal combustion engines. Thereby it will be shown in how far the performance of next generation hydrogen engines can be improved by implementing a direct fuel injection system instead of the conventional port injection approach. Results from numerical as well as from experimental investigations will be used to clearly give a vision of the overall future potential of hydrogen for combustion engines in comparison to fuel cell systems.
2008-09-09
Technical Paper
2008-32-0059
Franz Winkler, Roland Oswald, Oliver Schögl, Roland Kirchberger, Andreas Ebner
Based on the fundamental analysis of the two-stroke process (SETC 2005-32-0098) and the development of a stratified scavenged small capacity two-stroke engine (SETC 2006-32-0065), a further approach to achieve low emissions in this engine category is the main subject of this publication. The principles of the system are described by design activities, results of the 3D-CFD simulation and the visualization of the spray in the cylinder. The benefit of this system on exhaust emissions is demonstrated by engine test bench as well as chassis dynamometer results. The achievable reduction of exhaust emissions, especially with an applied oxidation catalytic converter, is remarkable and the potential to fulfill future emission limits has already been demonstrated.
2008-09-09
Technical Paper
2008-32-0042
Dalibor Jajcevic, Raimund A. Almbauer, Stephan P. Schmidt, Karl Glinsner
CFD simulation (Computational Fluid Dynamics) is a state of the art tool for the development of internal combustion engines, especially for internal mixture preparation, scavenging process and combustion. Simulation offers an array of information in the early development phase without the need of building a prototype engine. It shortens the development time, reduces the number of prototypes and therewith test bench costs. In previous investigations [SAE 2005-32-0099] and [SAE 2007-32-0030] a new coupling methodology which bases on the combination of three-dimensional (3D), one-dimensional (1D), and zero-dimensional (0D) CFD calculation has been presented. This methodology uses a new multidimensional interface technology and is able to handle 3D-0D, 3D-1D and 3D-3D connections. The special feature of this methodology is the capability of being placed on any position in the 3D CFD mesh.
2009-04-20
Technical Paper
2009-01-1420
Eichlseder Helmut, Schaffer Klaus, Leitner Daniel, Klell Manfred, Sartory Markus
Synergies in infrastructure and customer acceptance can be achieved by running internal combustion engines on mixtures of hydrogen and natural gas. Alongside the bridging effect between natural gas and hydrogen, such mixing offers advantages in terms of reduced emissions and improvements to the combustion process. The wide ignition limits and high flame speed of hydrogen have as positive an impact on the combustion of H2NG mixture as does the higher energy density of natural gas on range. A bi-fuel gasoline-natural gas vehicle was adapted to operation with gasoline, natural gas, hydrogen and any H2NG mixtures. For that purpose, the intake manifold was replaced by an aluminum construction, the injectors were replaced and the ECU had to be adjusted. Essentially quality-controlled hydrogen operation was possible throughout the engine map.
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