Chair in Automotive Powertrains

48V mild hybrid (MHEV) with partially homogeneous diesel combustion

Project duration: 01.01.2018 - 30.09.2020

Contact: Jan Klingenstein, M.Sc. and Andreas Schneider, M.Sc.

Abstract:

In the course of the increasingly stringent exhaust gas legislation and the planned introduction of type approval in real driving operation, ways must be found especially for the diesel engine to reduce the comparatively high nitrogen oxide and particulate emissions. In addition to the electrification of the powertrain, the adaptation of a partially homogeneous combustion process offers a further solution for mitigating this conflict of objectives. Especially for transient engine operation, the pronounced sensitivity of the partially homogeneous combustion to changed boundary conditions in the air and fuel path requires an exact control behavior of the combustion engine. The increased hydrocarbon emissions associated with this alternative combustion process require the use of an electrically heated catalytic converter in conjunction with the 48V on-board electrical system of a mild diesel hybrid. The aim of this research project is to develop and optimise the operating strategy for a diesel hybrid system with partially homogeneous combustion, taking exhaust aftertreatment into account. A phlegmatisation of the diesel engine with adapted combustion control allows the compensation of the air path inertia in transient phases and thus a further reduction of emissions. Within the framework of the project applied for, the concept for real, RDE-relevant driving conditions is to be optimised. If the test vehicle proves in the project that a concept in urban areas leads to a reduction of pollutant pollution, this is of overall economic and social interest.

Focus: Fuel and pollutant reduction through homogeneous diesel combustion process and electrification of the powertrain.

Funding: BMWi/AiF - Federal Ministry for Economic Affairs and Energy / German Federation of Industrial Research Associations

For further information on the project, please also contact the Research Association for Combustion Engines (FVV).

Powertrain 2040

Project duration: 01.04.2019 – 30.09.2021

Contact: Tobias Stoll, M.Sc.

Project Partners: University of Stuttgart, Institute for Acoustics and Building Physics (IABP)

Abstract:

Combinations of different powertrain concepts (combustion engines as hybrid or range extenders, fuel cells and pure e-vehicles) shall be simulated. Used components (engine type and size, gearboxes, direct drive option or not, battery size, etc.) shall be varied and simulated/optimised for different vehicle classes (see above). Fuel, electricity and component cost shall be varied to evaluate CO2 impact and TCO.

Focus: CO2 reduction

Comparison of consumption and environmental impact (CO2 emissions) of various future powertrain technologies over the entire life cycle of a vehicle.

Funding: Research Association for Combustion Engines eV

For further information on the project, please also contact the Research Association for Combustion Engines (FVV).

Piston Pin Bearing II

Project duration: 01.04.2017 bis 31.03.2020

Contact: Denise Branciforti, M.Sc.

Project Partners:

University of Kassel, Institute for Automotive Engineering

HAWK, Hildesheim/Holzminden/Göttingen

Institute for Analytical Measurement Technology Hamburg e. V., IAM-Hamburg e. V.

Abstract:

Increasing the operational safety of piston pin bearing arrangements. Within the framework of the completed research project "Piston pin bearing arrangements", the local temporal and spatial lubricant film formation in the piston- and conrod-side pin bearings could be identified as a significant influencing variable on the movement and load-bearing behaviour of the piston pin. Up to now, however, only insufficient knowledge is available about the exact transport mechanisms for the lubricant supply of the pin bearings, which are necessary for a simulation of the lubrication conditions at the bearing edges and inside. The aim of the project is to achieve an operationally reliable design of the piston pin bearing arrangement through an improved understanding of the oil supply situation and the identification of critical mixed friction and partial filling conditions. Experimental investigations will provide precise information on time-varying solid contacts in the bearing points, as well as friction coefficient maps depending on temperature, material pairing and lubricant condition. The results are compared with the simulation results and lead - based on the existing software - to an improved simulation model for the analysis and optimization of the piston pin bearing. With the help of the experimental and simulative findings, damage-relevant mechanisms are defined with the aim of achieving a reliable design and reducing CO2 emissions by minimizing friction.

Focus: Improvement of operational safety of piston pin bearing.

Definition of damage-relevant mechanisms of the piston pin bearing - reliable design and reduction of CO2 emissions by minimizing friction.

Funding: BMWi/AiF - Federal Ministry for Economic Affairs and Energy / German Federation of Industrial Research Associations / Research Association for Combustion Engines eV

For further information on the project, please also contact the Research Association for Combustion Engines (FVV).

Piston Conrod Dynamics II

Project duration: 01.01.2014 - 31.12.2016

Contact: Dipl.-Ing.  Wolfgang Gross

Project Partners:

University of Kassel, Institute for Automotive Engineering

Abstract:

Driven by stricter emission and fuel consumption regulations modern DI-Diesel enginies exhibit increasing combustion pressures. High combustion pressure in combination with high pressure gradients act as broadband excitation force, which stimulates natural vibrations of piston, conrod and crankshaft during engine operation. Starting from the combustion chamber the assembly of piston, conrod and crankshaft and the main bearings represent the system of internal vibration transfer which dominates the engine noise, as described in [1] and [2]. Based on the work carried out in the previous project “Piston Conrod Dynamics” this project serves to improve and extend the level of knowledge concerning the acoustic behavior of a modern EU6-Diesel engine with lightweight design components. To achieve this goal experimental and analytical investigations are carried out. First the modal behavior of single components and then the dynamic properties of the entire moving system were examined in detail in simulation and test as a base for the investigations. A successful correlation between experimental modal analysis (EMA) and Finite Element Analysis (FEA) forms the basis of model validation. The experimental investigations under fired conditions were done in an anechoic test bench to generate exact input and validation values for simulation models of structural dynamic and elastohydrodynamic coupled multi body systems. The measured values of combustion pressure, airborne and structure-borne sound allowed to identify the engine´s vibrational behavior in the whole operating range. After definition of a reference operating point various test series were carried out, such as injection timing and temperature variation. To understand the behavior of the conrod as the key component in more detail its elongation at the conrod shank during engine operation was also measured. The usage of semiconductor strain gauges allowed the recording of the natural vibrations of the conrod in a very accurate way up to a frequency about 10 kHz. Furthermore temperature measurements of piston and liner under fired conditions, allowed the determination of their warm contours using inverse methods. Variation of injection timing and conrod stiffness demonstrated main drivers for the dynamic behavior. In a further step measurement of the oil film thickness between the liner and the piston generated an improvement understanding of an unknown quantity in the simulation model. For this purpose the combination of inductive and capacitance measurements were used.

Focus: Calculation and measurement verification of dynamic contact forces between the piston and cylinder, taking into account transient thermal boundary conditions.

Funding: BMWi/AiF - Federal Ministry for Economic Affairs and Energy / German Federation of Industrial Research Associations / Research Association for Combustion Engines eV

For further information on the project, please also contact the Research Association for Combustion Engines (FVV).

Firing Friction Measurement Methodology

Project duration: 01.04.2018 - 31.09.2020

Contact: Kevin Huttinger, M.Sc.

Project Partners:

University of Kassel, Institute for Automotive Engineering

Abstract:

Increasing combustion pressure is inevitable in engine displacement reduction (downsizing). Even if the durability of the engines can be maintained, it is not desirable to increase the friction losses.
The friction depends mainly on the combustion pressure curve. In general, friction is assumed to be dependent on the magnitude of the combustion pressure. Depending on the characteristic of the pressure curve, i. e. magnitude and crank angle position of the peak pressure friction differences occur despite constant IMEP and engine speed. The reason is probably the change in lubrication condition. In engine development, the combustion pressure curve varies with the operating point and engine type, so the design should be optimized by taking this effect into account. In recent years the frequency of operating at low oil temperatures e.g. due to HEV has increased, which is why the optimization over a wide temperature range should be done. Therefore, the lubrication conditions and the friction as a function of the combustion pressure curve and the oil temperature have to be precisely simulated and validated by high-precision testing and measuring technology. As a result, the combustion process and oil temperature can be optimized at an early stage of development. At the same time, it should be possible to achieve equivalent durability with inexpensive bearings. Finally, it is desirable to to use the model within the FVV cylinder module.

Funding: Research Association for Combustion Engines eV

For further information on the project, please also contact the Research Association for Combustion Engines (FVV).

Reduction of Friction Losses by Local Management of the Oil Temperatures

Project duration: 01.11.2014 - 31.05.2018

Contact: Kevin Huttinger, M.Sc.

Abstract:

In real road traffic or in the NEDC cycle, car and truck engines are only operated at moderate loads and speeds. The oil temperatures occurring under these operating conditions are therefore far below the maximum permissible temperatures on which the operationally stable design of the engines was based. Due to the lower oil temperatures, however, the oil viscosities are much higher than the minimum permissible viscosities. This results in higher hydrodynamic friction losses than for operation at maximum oil temperature. Due to the low loads (cylinder pressures) in the operating ranges under consideration, the mixed friction component is low, so that this statement is also largely valid for the sum of hydrodynamic and mixed friction losses. By means of a controlled regulation of the oil supply temperature dependent on the operating condition (cylinder pressure, speed, etc.), oil at an elevated temperature should be supplied to the bearing points for "moderate operating conditions". It must be ensured by design that the bearing points are supplied with cooler oil as soon as the operating condition changes. The aim of the project should be, among other things, to measure and experimentally prove the reduction in frictional power.

Focus: Measurement and experimental verification of the friction power reduction. - Proof of a fast switchover to an oil supply with lower temperatures.

Funding: BMWi/AiF - Federal Ministry for Economic Affairs and Energy / German Federation of Industrial Research Associations

For further information on the project, please also contact the Research Association for Combustion Engines (FVV).

Pilot Ignition Gas Engine

Project duration: 01.08.2017-31.07.2020

Contact: Simon Hummel, M.Sc.

Abstract:

When using CNG as an alternative fuel, spark ignition systems are on the edge of their performance due to the required high ignition energies. Pilot ignition systems, which operate through a small quantity of directly injected liquid fuel (e.g. diesel), are a promising alternative to the common spark ignition. Therefore it will be investigated if different fuels injected with a standard gasoline DI-system can be used to ignite a homogeneous methane charge. This combustion strategy is used in large bore engines up to now, but the project is intended to evaluate the potential for passenger car engines. For this purpose, the pilot ignition spray is optically investigated with high speed photography and PDA technique to gain knowledge for the optimization of the atomization of different pilot ignition fuels. After those basic investigations, the combustion strategy is run in variations on a single cylinder research engine to assess performance, emissions and efficiency in detail.

Focus: Assessment of the potential of different fuels for a pilot ignited methane combustion in a passenger car engine.

Funding: BMWi/AiF - Federal Ministry for Economic Affairs and Energy / German Federation of Industrial Research Associations

For further information on the project, please also contact the Research Association for Combustion Engines (FVV).

Projektlaufzeit 01.06.2017 bis 31.05.2020

Projektpartner

Universität Stuttgart

IFS Lehrstuhl

Fahrzeugantriebe

Herr Prof. Dr.-Ing. M. Bargende

Herr Dipl.-Ing. Hans-Jürgen Berner

Ansprechpartner

Lehrstuhl Fahrzeugantriebe

Prof. Dr.-Ing. M. Bargende 

Hans-Jürgen Berner

Telefon 0711 685-65714

Optische Strahl-Analyse zur verbesserten 3D-CFD Simulation der Kraftstoff-Einspritzung in QuickSim

Ziel des Vorhabens ist die Nutzung eines PDA-Labors zur Durchführung optischer Kraftstoffstrahlanalysen, unter Verwendung unterschiedlichster Injektorgeometrien, zur grundlegenden Validierung der numerischen Beschreibung von Einspritzprozessen in der schnellen 3D-CFD Simulation (QuickSim) von Verbrennungsmotoren. Dazu müssen die laseroptischen Elemente des PDAPrüfstands hochpräzise ausgerichtet und justiert werden. Anschließend soll die Prüfstandssoftware ergänzt und nach einer Sensitivitätsanalyse der Toolkette in eine automatisierte Messdatenauswertung eingebettet werden. Durch die zeitliche und örtliche Sprayentwicklung, die sich aus den gemessenen Geschwindigkeits- und Tropfengrößenverteilungen ergibt, können die Startbedingungen des 3D-CFD Simulationstools QuickSim validiert und in einem iterativen Prozess verbessert werden.

Kernziele des Vorhabens sind Die sprayspezifischen Startbedinungen in der 3D-CFD Software QuickSim sollen auf der experimentellen Basis eines PDA-Prüfstandes, der dazu justiert und automatisiert werden muss, validiert und iterativ verbessert werden.

Fördermittelgeber Promotionsstipendium der Vector Stiftung

Modelling of Turbulence II

Project duration: 01.07.2016 - 31.07.2019

Contact: Sven Fasse, M.Sc.

Abstract:

Development of dynamic charge movement indices for quasidimensional turbulence modelling and dynamic flow coefficients for a more accurate charge exchange calculation.

So far, valve flow coefficients have been determined separately for inlet and outlet side, at low pressure ratio and synchronous valve lift. In real engine operation, the flow coefficients often deviate from this, partly due to valve train variability. These cases are now to be modeled for the 0D/1D engine simulation. This also includes the conversion of a previously empirical to a phenomenal inflow turbulence model and the extension of an existing tumble charge movement and turbulence model for combined swirl-tumble charge movements.

Focus:

• Development of valve flow coefficients for high pressure conditions, flow pulsation, valve overlap and inlet valve lift phase/channel shut-off
• Development of a phenomenological inflow turbulence model
• Development of a charge movement and turbulence model for combined twist-tumble charge movement

Funding: BMWi/AiF - Federal Ministry for Economic Affairs and Energy / German Federation of Industrial Research Associations

For further information on the project, please also contact the Research Association for Combustion Engines (FVV).

Homogenisation Model SI Engine

Project duration: 01.01.2017 - 30.06.2019

Contact: Sebastian Fritsch, M.Sc.

Abstract:

Due to numerous advantages, direct injection can be considered a standard technology in modern gasoline engines. Its influence on in-cylinder turbulence, however, cannot be accounted for in existing zero- and one-dimensional models. The objective of this project is thus to develop corresponding sub-models and to integrate them in existing turbulence, burn rate and cycle-to-cycle variation models. In this way, a valuable increase in predictive power can be achieved. The solution process follows the approach of the successful predecessor project. At first, the influence of direct injections on charge motion (e. g. tumble) is to be analyzed based on 3d-CFD calculations in order to enhance the existing turbulence model. Correspondingly, 3d-CFD simulations are used as reference to develop a phenomenological homogenization model based on key parameters of the gas exchange cycle, the enhanced charge motion and turbulence model and characteristic numbers (to be developed). The homogenization model then has to be integrated in an appropriate way into the existing burn rate and cycle-to-cycle variation models. As a result, improved models will be available that allow predictive simulations of the influence of direct injections for the first time in the 0d/1d domain. This enables, for instance, an efficient development of multiple injection strategies for improved mixture homogenization as well as accounting for differences in homogenization when using variable valve timings.

Focus: Development of a quasi-dimensional model describing the interaction of direct injection and charge motion as well as homogenisation of the trapped mass considering different gas exchange strategies

Funding: BMWi/AiF - Federal Ministry for Economic Affairs and Energy / German Federation of Industrial Research Associations

For further information on the project, please also contact the Research Association for Combustion Engines (FVV).

Thermodynamics Top Land Volume

Project duration: 01.01.2017 - 31.03.2020

Contact: Dipl.-Ing. Hans-Jürgen Berner, Markus Koch, M.Sc.

Abstract:

Analysis and physically/chemically based modeling through an energy-balance of the influences of the time-varying unburnt mass fraction in wall proximity and in the top land. At first, the influence of near wall zones and the top land volume on the combustion chamber in the combustion phase after reaching peak pressure shall be investigated experimentally with a focus on modeling. Based on these findings, a model to describe the near wall phenomenon of the heat release through an energy-balance shall be developed. A better understanding of the interactions between top land volume and combustion chamber is a necessary boundary condition to describe the effects of the unburnt mixture mass in the top land and to make it useable in analysis and simulation.

Focus: A better understanding of the interaction between top land volume and combustion chamber Description of the effects of the unburnt mixture mass in the top land.

Funding: BMWi/AiF - Federal Ministry for Economic Affairs and Energy / German Federation of Industrial Research Associations / Research Association for Combustion Engines eV

For further information on the project, please also contact the Research Association for Combustion Engines (FVV).

Methane Fuels II

Project duration: 01.04.2016 - 31.12.2019

Contact: Dipl.-Ing. Marcel Eberbach und Sebastian Hann, M.Sc.

Abstract:

Identifying, quantifying and modelling of the impact of selected components of methane-based fuels on the heat release in Otto-cycle operation.

Funding: Research Association for Combustion Engines eV

For further information on the project, please also contact the Research Association for Combustion Engines (FVV).

Projektlaufzeit 15.04.2016 bis 14.04.2019

Projektpartner  Audi AG

Ansprechpartner

Lehrstuhl Fahrzeugantriebe

Herr Prof. Dr.-Ing. M. Bargende 

Dipl.-Ing. Hans-Jürgen Berner

Telefon +49 711 685-65714

Methodische Untersuchung und ganzheitliche Potentialbewertung zukünftiger Antriebskonzepte zur CO2 - Neutralität im Rennsport

Die globale Erwärmung aufgrund von Treibhausgasemissionen stellt eine der größten Herausforderungen für die Menschheit dar und fordert die Automobilindustrie. Aufgrund seiner Vorreiterrolle ist auch der Motorsport mit dieser Problemstellung konfrontiert und hat die Aufgabe die Entwicklung von technischen Lösungen zur Reduzierung der Umweltauswirkungen voranzutreiben. Erste Schritte in Richtung Nachhaltigkeit sind die Effizienzreglements, die 2014 in der FIA Formel 1 und der FIA World Endurance Championship eingeführt wurden, sowie die Beimischung von Biokraftstoffen und die Einführung von Hybridsystemen in diesen beiden Rennserien. Der Fokus auf globale Nachhaltigkeit und die Integration dieses Aspektes in das Reglement steht jedoch noch aus. Daher werden im Rahmen des Promotionsprojektes nachhaltige Hochleistungskonzepte für den Langstreckenrennsport ganzheitlich umweltbilanziell und technologisch untersucht.

Kernziele des Vorhabens sind

Umweltbilanzielle und technologische Untersuchung diverser Antriebskonzepte und Kraftstoffe für den Einsatz in einem nachhaltigen Motorsport der Zukunft.

Projektlaufzeit 01.01.2018 bis 31.12.2019

Projektpartner
Universität Stuttgart IFS Lehrstuhl Fahrzeugantriebe Herr Prof. Dr.-Ing. M. Bargende Herr Dr.-Ing. Michael Grill

Ansprechpartner

Lehrstuhl Fahrzeugantriebe

Prof. Dr.-Ing. M. Bargende

Dr.-Ing. Michael Grill

Qirui Yang

Telefon +49 711 685-65611

Auswirkungen auf Luftpfad, Ladungswechsel und Abgassystem bei der optimierten Auslegung von Dieselmotoren für den eFuel OME zum Einsatz in Fernstrecken-Lkw

Bei Fernstrecken-Lkw werden batterieelektrische Antriebe aufgrund des Verlustes an Nutzlast und Reichweite auch langfristig die Ausnahme bleiben. Um dennoch CO2-Neutralität zu erreichen, erscheint der Einsatz von strombasierten, synthetischen Kraftstoffen (eFuels) als sinnvoller Weg, speziell die Gruppe der Oxymethylenether (OME) als Ersatz für konventionellen Dieselkraftstoff gilt hier wegen seiner rußfreien Verbrennung als vielversprechend. Die Auswirkungen des Einsatzes von OME wirken sich dabei vielfältig auf Luftpfad, Ladungswechsel und Abgassystem und andere Subsysteme des Fahrzeugs aus.

Kernziele des Vorhabens sind

Ziel des Vorhabens ist daher, diese Auswirkungen detailliert zu analysieren und den Weg für eine Praxisanwendung zu ebnen, die einen enormen Beitrag für eine bessere Umweltverträglichkeit – sowohl hinsichtlich Schadstoffemissionen als auch in Bezug auf den Treibhauseffekt – speziell des Güterverkehrs zu leisten im Stande ist.

Projektförderung Fördermittelgeber Friedrich und Elisabeth Boysen-Stiftung

Partially Premixed Diesel Combustion

Project Duration: 01.01.2019 - 31.12.2020

Contact: Dipl.-Ing. Hans-Jürgen Berner, Marvin Wahl, B.Sc., Viktoria Kelich, M.Sc.

Project Partner: ETH Zürich, Aerothermochemistry and Combustion Systems Laboratory (LAV)

Abstract:

The partially premixed compression ignition (PCCI) is regarded as a promising diesel combustion concept for extremely low emissions with high process controllability. For low load/rev engine operating points, PCCI has already demonstrated the simultaneous reduction of soot and NOx raw emissions and thus demonstrated a way out of the existing NOx/soot conflict of conventional diesel combustion. Current research & development in the field of diesel combustion, especially in optimization processes, is based on numerical methods. Reliable phenomenological combustion and ignition delay models have proven to be particularly suitable for parameter studies. However, most ignition delay models have been developed for conventional diesel combustion.

Therefore, in this project new ignition delay models shall be presented which predict the ignition delays for PCCI operation with multiple injections for the 0D simulation. For this purpose, measurements will be performed on a single-cylinder unit to characterize PCCI combustion and provide data for subsequent model generation and validation.

The work at the IFS will be carried out in cooperation with the ETH Zurich. There, 3D-CRFD simulation calculations with detailed chemical kinetics will be carried out in parallel and comprehensive combustion models will be added.

Project targets:
Creation of a simulation model for the predictive calculation of the combined physical-chemical ignition delay in partially homogeneous diesel combustion processes with multiple injection.

Funding:

CORNET - Collective Research Networking

BMWi/AiF - Federal Ministry for Economic Affairs and Energy / German Federation of Industrial Research Associations

FVV - Research Association for Combustion Engines eV

For further information on the project, please also contact the Research Association for Combustion Engines (FVV).

Dual Fuel CI Engines

Project duration: 01.01.2016 - 31.12.2018

Contact: Dr.-Ing. Michael Grill and Viktoria Kelich, M.Sc.

Abstract:

To reduce carbon dioxide emissions in commercial vehicles, natural gas can be used as an alternative fuel with methane as the main component. Due to the carbon/hydrogen atomic ratio, methane produces about 20% less carbon dioxide emissions for the same amount of energy compared to gasoline or diesel. In the research project, a dual-fuel concept was modelled. The engine should continue to be usable without restriction for pure diesel operation; in dual-fuel operation, approx. 20 to 80% of the diesel fuel is then replaced by natural gas.

Within the framework of the research project, a phenomenological combustion process model was developed and validated. The model is based on extensive measurement data from the research project. On the other hand, the findings of 3D CFD calculations and tests on a long-stroke compression machine, which were carried out as part of the research project at ETH Zurich. The model depicts physical and chemical processes and contributes to the knowledge of the internal engine phenomena during diesel combustion on a homogeneous base mixture.

The basis of the model development was an intensive measurement data analysis. For this purpose, among other things, the diesel portion of dual-fuel combustion was simulated with a well-tuned diesel combustion process model in order to gain information on the time sequence of CNG conversion via the difference between the total combustion process from the measurement data analysis and the modelled diesel conversion.

Funding: BMWi/AiF - Federal Ministry for Economic Affairs and Energy / German Federation of Industrial Research Associations

For further information on the project, please also contact the Research Association for Combustion Engines (FVV).

Schlussbericht

Post-Oxidation (HC, CO and particles) inside the exhaust manifold of SI engines

Project duration: 01.10.2018 - 30.09.2020

Contact: Rodolfo Tromellini, M.Sc., Jan Przewlocki, M.Sc. and Viktoria Kelich, M.Sc.

Project Partners:

Chiba University National University, Japan

Meiji University, Japan

Abstract:

The introduction of more dynamic driving cycles for car type approval, such as WLTP or even real driving measurements (RDE), requires an improvement in transient engine behaviour while minimising emissions. The post-oxidation of rich combustion products in the exhaust manifold with scavenging air is a promising measure to achieve this goal.

Purging the cylinder reduces the residual gas content, reduces the combustion chamber temperature and the increased mass flow improves the dynamic behaviour of the turbocharger. The resulting excess oxygen impedes effective operation of the three-way catalytic converter. One way to solve this problem is to bind the excess oxygen by oxidation with the products of rich combustion from the combustion chamber. This allows the dynamic behaviour of the turbocharger to be further improved by increasing the enthalpy of the exhaust gases. Rich combustion also lowers the temperature in the combustion chamber, which reduces the tendency to knock. Another benefit of post-oxidation is the possibility of heating the catalyst up to operating temperature more quickly.

The aim of this project is to develop a post-oxidation model for 0D/1D simulation. In order to develop this model, a deep understanding of the critical mixing and oxidation process of scavenging air and rich combustion products is required.

Within this project, 3D-CFD simulations including reaction kinetics in combination with test bench measurements will be performed. To reduce the 3D-CFD computation time, a reduced reaction mechanism covering all important chemical processes of post-oxidation will be developed.

The post-oxidation model developed in the course of the project will be extended based on test bench measurements in order to map processes within the turbine.

Finally, a RDE driving cycle will be simulated to demonstrate the potential of post-oxidation and to evaluate the influence of critical acceleration maneuvers on the applicability to post-oxidation.

Focus: Development of a post-oxidation model within the 0D/1D domain.

Funding:

FVV - Research Association for Combustion Engines eV

CORNET - Collective Research Networking

BMWi/AiF - Federal Ministry for Economic Affairs and Energy / German Federation of Industrial Research Associations

For further information on the project, please also contact the Research Association for Combustion Engines (FVV).

Exhaust Gas Aftertreatment Before Turbine

Project duration: 01.05.2018 - 31.12.2020

Contact: Martin Angerbauer, M.Sc.

Project Partners: TU Berlin, Institute of Land and Sea Transport Systems (VKM)

Abstract:

A more stringent legislation concerning gaseous and particle emission is expected. Therefore, a more detailed knowledge of emission generation is mandatory to find levers for a reduction of the respective pollutants.

Focus: Research work should answer the following issues:
• Layout for exhaust aftertreatment system u/s TC => e.g. DOC / LNT and optional cDPF / SDPF
• Impact of catalysts and particulate filters on turbocharger systems => gas flow, impuls, enthalpie, efficiency, durability, conversion efficiency, …
• Impact of upstream turbine position to catalysts (pressure level, pressure fluctuation, peak temperatures and temperature level, conversion efficiency)
• Analysis and countermeasures for transient response => Supercharging concepts, boost pressure control
• Temperature control of catalysts, DPF and turbine => catalyst heat-up and active DPF regeneration

Funding: Research Association for Combustion Engines eV

For further information on the project, please also contact the Research Association for Combustion Engines (FVV).

Fast Knocking Prediction for Gasoline Engines

Project duration: 01.10.2019 - 30.09.2021

Contact: Nicolas Fajt, M.Sc.

Project Partners:

RWTH Aachen, Institute for Combustion Engines (VKA)

Abstract:

Development of a methodology for predictive, fast and robust 0D-simulation tool accounting for knocking combustion and cycle-to-cycle variation in gasoline engines with consideration for stochastic nature of these phenomena, fuel effects and their interactions.  The development efforts to improve fuel efficiency of spark ignition (SI) engines are aimed at reducing the tendency to knocking combustion and improving combustion stability that is related to cycle-to-cycle variation (CCV). The stochastic nature of these phenomena makes their reliable and fast simulation be a challenging and so far not resolved task. In consequence, most of simulation methods rely almost exclusively on an extensive experimental data for simulating engine knock.  This drawback can be avoided by the application of a stochastic reactor modeling approach and using the detonation diagram by Bradley for knock identification. However, the overall validity of the conditions for developing detonation borderlines on the detonation diagram has not been verified yet (e.g. for different gasoline surrogates, engine types and operating conditions).

Focus: Development of a fast and robust simulation tool for knocking prediction of gasoline engines.

Funding: Research Association for Combustion Engines eV

For further information on the project, please also contact the Research Association for Combustion Engines (FVV).

HC/CO-Model

Project duration: 01.01.2018 - 30.04.2020

Contact: Christian Schnapp, M.Sc.

Abstract:

This project aims to develop a phenomenological 0D/1D-approach to simulate the formation of the in-engine raw emissions of unburnt hydrocarbons and carbon monoxide for diesel engines. The model should be able to predict the HC and CO emissions for both stationary and transient operating conditions. The results provided by the model for the HC and CO formation are not only relevant for the prediction of the emissions themselves and furthermore the exhaust after-treatment and the regeneration of the exhaust after-treatment system. In addition depending on the operating point these emissions are relevant to correctly predict the efficiency and therefore the fuel consumption of diesel engines.
To predict the formation of HC and CO the model has to represent the relevant inhomogeneities during the combustion in diesel engines. For this purpose, the locally lean and rich areas are especially important. Additionally, for the formation of HC the wall quenching, that is the flame quenching in close proximity to the combustion chamber wall, is relevant. In combination with highly simplified chemical reaction mechanisms the modelling of these inhomogeneities allow the prediction of the formation of HC and CO.

Focus: Simulation of the formation of raw emissions of unburned hydrocarbons and carbon monoxide for diesel engines.

Funding: BMWi/AiF - Federal Ministry for Economic Affairs and Energy / German Federation of Industrial Research Associations

For further information on the project, please also contact the Research Association for Combustion Engines (FVV).

Fuel Composition for CO2 Reduction

Project duration: 01.03.2019 - 28.02.2022

Contact: Sebastian Croenert, M.Sc.

Project Partners:

RWTH Aachen, Institute for Combustion Engines (VKA)

RWTH Aachen, Physico-Chemical Fundamentals of Combustion (ITV)

Brandenburg University of Technology Cottbus-Senftenberg, Institute for Electrical and Thermal Energy Systems, Chair of Thermodynamics/Thermal Process Engineering

Abstract:

Economic motivation: Reducing CO2 emission is world-wide common issues. To correspond to the issues throughout the world, new generation fuels which enhance flame propagation and mitigate knocking should be considered in addition to the argument on E-fuel. The new generation fuels enhance engine thermal efficiency and reduce emission.
Scientific motivation: Low temperature combustion and mitigating knocking are effective ways to enhance engine thermal efficiency. To realize the concepts, understanding the effect of turbulence intensity and chemical reaction on combustion is necessity. Since this understanding is fundamental research , the scope of application is wide, such as combustion modeling and elementary reaction modeling.

Focus: The object is to clarify the effect of new generation fuels on how they contribute to enhance thermal efficiency and reduce emissions.

Funding: Research Association for Combustion Engines eV.

For further information on the project, please also contact the Research Association for Combustion Engines (FVV).

Spray Modelling for DI Gasoline Engines

Project duration: 01.01.2019 - 31.12.2021

Contact: Cornelius Wagner, M.Sc. and Viktoria Kelich, M.Sc.

Project Partners:

TH Nuremberg, Institute for Automotive Engineering (IFZN)

Abstract:

Latest emissions legislation (RDE) have highly increased the performance requirement from the injection and combustion process. An optimised control of the injection process in terms of mixture formation and cylinder wall impingement is needed in a wide range of operating conditions including catalyst heating or cold start. In the case of DI gasoline engines the trend of spray strategy is becoming increasingly complex due to the increasing number of injections per cycle at different injection system and engine cylinder pressures and the variety of different fuel blends which affect penetration, shape and mixture formation. The typical development tool to have accurate prediction of the injection process is based on CFD spray simulation which provides accurate results but it is computationally expensive and not optimal for screening a large amount of injection variables nor for control strategy development.

Focus: The aim of this project is the development of a simulation tool able to predict the spatial distribution of a transient spray in terms of fuel velocity, mass and equivalence ratio. The tool should work for multiple injections and for different fuel blends (i.e gasoline-ethanol).

Funding: Research Association for Combustion Engines eV

For further information on the project, please also contact the Research Association for Combustion Engines (FVV).

Thermodynamics Top Land Volume

Project duration: 01.01.2017 - 31.03.2020

Contact: Dipl.-Ing. Hans-Jürgen Berner, Markus Koch, M.Sc.

Abstract:

Analysis and physically/chemically based modeling through an energy-balance of the influences of the time-varying unburnt mass fraction in wall proximity and in the top land. At first, the influence of near wall zones and the top land volume on the combustion chamber in the combustion phase after reaching peak pressure shall be investigated experimentally with a focus on modeling. Based on these findings, a model to describe the near wall phenomenon of the heat release through an energy-balance shall be developed. A better understanding of the interactions between top land volume and combustion chamber is a necessary boundary condition to describe the effects of the unburnt mixture mass in the top land and to make it useable in analysis and simulation.

Focus: A better understanding of the interaction between top land volume and combustion chamber Description of the effects of the unburnt mixture mass in the top land.

Funding: BMWi/AiF - Federal Ministry for Economic Affairs and Energy / German Federation of Industrial Research Associations / Research Association for Combustion Engines eV

For further information on the project, please also contact the Research Association for Combustion Engines (FVV).

Homogenisation Model SI Engine

Project duration: 01.01.2017 - 30.06.2019

Contact: Sebastian Fritsch, M.Sc.

Abstract:

Due to numerous advantages, direct injection can be considered a standard technology in modern gasoline engines. Its influence on in-cylinder turbulence, however, cannot be accounted for in existing zero- and one-dimensional models. The objective of this project is thus to develop corresponding sub-models and to integrate them in existing turbulence, burn rate and cycle-to-cycle variation models. In this way, a valuable increase in predictive power can be achieved. The solution process follows the approach of the successful predecessor project. At first, the influence of direct injections on charge motion (e. g. tumble) is to be analyzed based on 3d-CFD calculations in order to enhance the existing turbulence model. Correspondingly, 3d-CFD simulations are used as reference to develop a phenomenological homogenization model based on key parameters of the gas exchange cycle, the enhanced charge motion and turbulence model and characteristic numbers (to be developed). The homogenization model then has to be integrated in an appropriate way into the existing burn rate and cycle-to-cycle variation models. As a result, improved models will be available that allow predictive simulations of the influence of direct injections for the first time in the 0d/1d domain. This enables, for instance, an efficient development of multiple injection strategies for improved mixture homogenization as well as accounting for differences in homogenization when using variable valve timings.

Focus: Development of a quasi-dimensional model describing the interaction of direct injection and charge motion as well as homogenisation of the trapped mass considering different gas exchange strategies

Funding: BMWi/AiF - Federal Ministry for Economic Affairs and Energy / German Federation of Industrial Research Associations

For further information on the project, please also contact the Research Association for Combustion Engines (FVV).

Partially Premixed Diesel Combustion

Project Duration: 01.01.2019 - 31.12.2020

Contact: Dipl.-Ing. Hans-Jürgen Berner, Marvin Wahl, B.Sc., Viktoria Kelich, M.Sc.

Project Partner: ETH Zürich, Aerothermochemistry and Combustion Systems Laboratory (LAV)

Abstract:

The partially premixed compression ignition (PCCI) is regarded as a promising diesel combustion concept for extremely low emissions with high process controllability. For low load/rev engine operating points, PCCI has already demonstrated the simultaneous reduction of soot and NOx raw emissions and thus demonstrated a way out of the existing NOx/soot conflict of conventional diesel combustion. Current research & development in the field of diesel combustion, especially in optimization processes, is based on numerical methods. Reliable phenomenological combustion and ignition delay models have proven to be particularly suitable for parameter studies. However, most ignition delay models have been developed for conventional diesel combustion.

Therefore, in this project new ignition delay models shall be presented which predict the ignition delays for PCCI operation with multiple injections for the 0D simulation. For this purpose, measurements will be performed on a single-cylinder unit to characterize PCCI combustion and provide data for subsequent model generation and validation.

The work at the IFS will be carried out in cooperation with the ETH Zurich. There, 3D-CRFD simulation calculations with detailed chemical kinetics will be carried out in parallel and comprehensive combustion models will be added.

Project targets:
Creation of a simulation model for the predictive calculation of the combined physical-chemical ignition delay in partially homogeneous diesel combustion processes with multiple injection.

Funding:

CORNET - Collective Research Networking

BMWi/AiF - Federal Ministry for Economic Affairs and Energy / German Federation of Industrial Research Associations

FVV - Research Association for Combustion Engines eV

For further information on the project, please also contact the Research Association for Combustion Engines (FVV).

Water Injection in SI Engines

Project duration: 01.04.2017 - 30.11.2019

Contact: Antonino Vacca, M.Sc.

Project Partners:

TU Berlin, Institute of Land and Sea Transport Systems (VKM)

Brandenburg University of Technology Cottbus-Senftenberg, Institute for Electrical and Thermal Energy Systems, Chair of Thermodynamics/Thermal Process Engineering

Abstract:

Within this research project we develop modles and numerical methods, which allow the evaluation of engine developments with water injection. These will help to utilize the potential of water injection in spark ignition engines to optimize power and efficiency. Model extensions concentrate on the physics of water and emulsion sprays, the changed thermodynamic engine cycle, as well as the influence of high water concentrations on the reaction kinetics in the gas phase, as well in catalysts. The project applies 3D CFD and 1D/Q3D methods.
A comprehensive experimental data base will be established to support the model development. The particularly spray properties will be investigated in spray chambers and in a rapid compression machine. The latter will allow conditions close to the critical thermodynamic state of water sprays. Experiments in a single cylinder engine will analyse the thermodynamic properties of gases with high water content, and of expanding gases under simultanous water vaporisation. These experiments also allow to investigate changes in the reaction kinetics, through heat release and engine out emission concentration measurements. Representative experiments at a catalyst test bench will finally judge the influence of increased water concentrations on the reactivity of catalysts.
The utilizations of the developed methods and models will be demonstrated by the help of a regular engine model. The project delivers the comprehensive experimental data base, a detailed discription of all developed models and methods, comprehensive data for reaction kinetics for gas base and surface reactions and an extension of the FVV cylinder module. This extension is based on detailed 3D CFD and 1D/Q3D validation calculations.Focus: CO2 reduction

Evaluation of the potential und risks of the direct water injection to increase efficiency and load in spark-ignition engines.

Funding: Research Association for Combustion Engines eV

For further information on the project, please also contact the Research Association for Combustion Engines (FVV).

Water Injection in SI Engines II

Project duration: 01.10.2019 - 31.03.2022

Contact: Edoardo Rossi, M.Sc.

Project Partners:

TU Berlin, Institute of Land and Sea Transport Systems (VKM)

Brandenburg University of Technology Cottbus-Senftenberg, Institute for Electrical and Thermal Energy Systems, Chair of Thermodynamics/Thermal Process Engineering

Abstract:

The project FVV water injection in SI engines delivered an insight for the effects of water injection on the injector performance and in-cylinder thermodynamics and chemistry using single-cylinder experiments and simulations. However, there are still open question of the working group that should be answered by a follow-up project. The first topic is a more detailed understanding of the mixture formation with advanced injector technologies, e.g. 500 bar injection pressures, emulsion injection and multi-injection strategies. Potentials of modification of the hardware to increase the benefit of the water injection should be investigated and understood in detail. Further, the combination of water injection with variable valve timing and exhaust gas recirculation shall be investigated. The questions shall be answered how these technologies influence each other and what potentials of combination of these technologies are available over the engine map. The investigation of the effects of changes of exhaust gas composition and exhaust temperature due to water injection and exhaust gas recirculation on the emission conversion in Three-Way-Catalysts and Gasoline-Particle-Filters shall be understood more in detail and transferred to robust and reliable simulation models. The obtained knowledge and models can be used by the OEMs and suppliers to improve their product development, also with regard with future RDE legislation.

Focus: Evaluation of the potential und risks of the water injection to increase efficiency and load in spark-ignition engines

Funding: Research Association for Combustion Engines eV

For further information on the project, please also contact the Research Association for Combustion Engines (FVV).

Water Injection on Diesel Engines

Project duration: 01.11.2018 - 31.10.2020

Contact: Sebastian Welscher, M.Sc. and Antonino Vacca, M.Sc.

Project Partners: Karlsruhe Institute of Technology (KIT), IFKM

Abstract:

Against the backdrop of increasing climate awareness and the introduction of much stricter exhaust emission legislation, the further development of the diesel engine faces major challenges. In addition to reducing fuel consumption in order to maintain fleet consumption, emissions of pollutants must be reduced under more demanding conditions. These targets are increasingly difficult to achieve with conventional diesel engines based on the current state of technology. On the one hand, the complexity of the overall "diesel engine" system has already reached a very high level, which offers hardly any room for remarkable leaps in development. On the other hand, the above-mentioned objectives usually have opposing effects, so that a solution found is often only a compromise.

In order to defuse this conflict and to demonstrate new development potential, water injection in diesel engines is therefore being investigated as part of this research project. In the past, this technology has already been used successfully, especially in aircraft and ship engines. Currently, this technology is finding a growing application in the field of gasoline engines.

While the main focus in gasoline engines is on increasing performance, water injection in diesel engines is being investigated primarily with regard to pollutant emissions. Due to the lower peak temperatures caused by the evaporation of the water in the intake manifold or cylinder, internal engine nitrogen oxide production can be significantly reduced. In conjunction with other measures such as throttling the exhaust gas recirculation rate (EGR), positive effects on soot oxidation and efficiency can also be expected.

In order to correctly map potential effects and take them into account during development, it is necessary to make them available for engine simulation after a detailed investigation.

For this purpose, the correct modelling of the ignition delay and the combustion process as a function of the injected amount of water is particularly necessary in order to precisely calculate a modified diesel engine combustion, which in turn forms the basis for a correct mapping of pollutant emissions. If necessary, the models of the latter must also be adapted according to the results of the investigations.

After implementation of the findings into the 0D/1D simulation, the development of possible application strategies for water injection in real operation is planned. The basis for this are the newly created or adapted calculation models. An evaluation and potential analysis concludes the project.

The project is carried out in cooperation with the Institut für Kolbenmaschinen (IFKM) in Karlsruhe (Karlsruhe Institute of Technology, KIT). In parallel to the simulative investigations and modelling work of the Institut für Fahrzeugtechnik Stuttgart Stuttgart (IFS), extensive measurements will be carried out on a modified engine test bench. These results serve as a basis and extension of the understanding of the effects of water injection on diesel combustion and are included in the modelling and validation. IFS, on the other hand, works exclusively on the simulation scope of this project. The latter include modelling and simulation in the 0D/1D range as well as 3D-CFD investigations.

Focus:

• Investigation, modelling and simulation of effects of water injection on diesel combustion
• Development and investigation of possible application strategies for water injection in real operation

Funding: BMWi/AiF - Federal Ministry for Economic Affairs and Energy / German Federation of Industrial Research Associations

For further information on the project, please also contact the Research Association for Combustion Engines (FVV).

VVT for Diesel LNT Rich Purge

Project duration: 01.04.2017 - 31.07.2020

Contact: Michael Brotz, M.Sc. und Markus Maul, M.Sc.

Abstract:

The rich operation for LNT regeneration with a combustion air ratio of lambda ~ 0.95 is usually achieved by intake air throttling and high external EGR rates. This procedure leads to low combustion stability in the diesel engine at low engine load. For this reason, LNT regeneration below a certain load limit is not possible or very difficult. In conventional NEDC-based legislation, regeneration is therefore usually carried out in the EUDC part of the test. In RDE low-load operation, especially at low outside temperature and/or altitude, LNT regeneration poses a problem.

Variable valve lift strategies such as the exhaust secondary lift can significantly stabilise combustion at low load by means of hot internal EGR. As initial spot tests show, the higher process temperature curve results in increased formation of carbon monoxide (CO) and less formation of hydrocarbons (HC). This shift in the exhaust gas composition is advantageous for LNT regeneration.

The objective is to achieve improved and more flexible diesel LNT regeneration throughout the entire engine map with the aid of variable valve control strategies. Within the scope of the tests, it will be investigated whether discretely switchable valve lift curves are sufficient for optimum regeneration behaviour at low load, or whether a continuously variable system is required. Furthermore, it will be investigated whether the increase in soot particle emission can be reduced by a targeted design of the exhaust double lift strategy in combination with the inlet valve lift strategy.

The benefit lies in the evaluation of a technology module that may be relevant for the fulfilment of future RDE legislation. In previous FVV projects this potential of variable valve lift strategies has not been investigated.

Focus: Assessment of internal EGR by variable valve actuation with the aim to stabilize rich combustion for Diesel LNT rich purge at low engine loads

Funding: BMWi/AiF - Federal Ministry for Economic Affairs and Energy / German Federation of Industrial Research Associations.

For further information on the project, please also contact the Research Association for Combustion Engines (FVV).

Project duration: 01.05.2018 – 30.04.2021

Contact: Ralf Kleisch, M.Sc.

Abstract:

Today ongoing electrification of automobiles leads to a variety of different drivetrain architectures.

In particular hybrid powertrain configurations including an internal combustion engine and one or more electric machines, make up a majority of the possible architectures. In order to select

the right powertrain from this variety, based on the right choice of topology as well as the determination of the individual components, an optimization tool is needed which is able to evaluate and identify optimal powertrain concepts on the basis of specific driving demands.

To be able to handle the great variety of concepts, these optimal drive trains will be calculated in different stages.

The calculation steps will be carried out by the developed tool chain, which calculates a predefined driving request using different optimization algorithms for multiple drivetrain configurations and different degrees of granularity.

Focus: Simulation-based identification of optimal hybrid powertrain configurations regarding topology and component dimensioning

Funding: Promotionskolleg HYBRID

Accurate Temperature Management

Project duration: 01.03.2017 - 31.08.2019

Contact: Dipl.-Phys. Florian Mandl

Abstract:

1D and 3D-CFD comprehensive development methodology for the optimization of the engine water jacket, from concept to production maturity.

The industry is working intensively on the precision of thermal management at system level. By using complex thermal management strategies, it is possible to make heat distribution more precise and dynamic, thus increasing efficiency. Considerable efforts are also being made to improve the cooling efficiency of the engine water jacket using 3D-Computational Fluid Dynamics (CFD). In going through the V-optimization process from conception to the design phase and back to the performance evaluation of the overall system, industry relies on analytical models (Nusselt) and attempts to work out heat transfer coefficients according to Prandtl and Reynolds numbers. However, Nusselt is not applicable to modern water jacket concepts due to complex flow structures. The aim of this project is to define the application range of a classical Nusselt approach for a modern water jacket concept and to find extensions or alternatives if necessary. The technical benefit of the project lies in the development of a practice-oriented, comprehensive method for the optimization of the engine water jacket from conception to production maturity. This should lead to a better combination of 1D and 3D-CFD, which ultimately accelerates and secures the entire development process.

Focus: Development of a practice-oriented, comprehensive method for the optimization of complex engine water jackets from conception to production maturity, which should enable a more efficient combination of 1D and 3D-CFD.

Funding: BMWi/AiF - Federal Ministry for Economic Affairs and Energy / German Federation of Industrial Research Associations

For further information on the project, please also contact the Research Association for Combustion Engines (FVV).

Abschlussbericht