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Experimental and Numerical Analysis of Pre-Chamber Combustion Systems for Lean Burn Gas Engines

Volkswagen AG-Gunesh Tallu, Gwendal Lucas, Michael Weissner
Ricardo UK Ltd-Evgeniy Shapiro, Nick Tiney
Published 2019-04-02 by SAE International in United States
The current trend in automobiles is towards electrical vehicles, but for the most part these vehicles still require an internal combustion engine to provide additional range and flexibility. These engines are under stringent emissions regulations, in particular, for the reduction of CO2. Gas engines which run lean burn combustion systems provide a viable route to these emission reductions, however designing these engines to provide sustainable and controlled combustion under lean conditions at λ=2.0 is challenging. To address this challenge, it is possible to use a scavenged Pre-Chamber Ignition (PCI) system which can deliver favorable conditions for ignition close to the spark plug. The lean charge in the main combustion chamber is then ignited by flame jets emanating from the pre-chamber nozzles. Accurate prediction of flame kernel development and propagation is essential for the analysis of PCI systems. A modelling approach is proposed based on the Dynamic Discrete Particle Ignition Kernel model coupled with the G-equation combustion model. The model is validated for an air/methane academic benchmark. The approach is then applied to the investigation of…
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Investigation of an Innovative Combustion Process for High-Performance Engines and Its Impact on Emissions

Volkswagen AG-Donatus Wichelhaus
FKFS-Marco Chiodi, Andreas Kaechele
Published 2019-01-15 by SAE International in United States
Over the past years, the question as to what may be the powertrain of the future has become ever more apparent. Aiming to improve upon a given technology, the internal combustion engine still offers a number of development paths in order to maintain its position in public and private mobility. In this study, an innovative combustion process is investigated with the goal to further approximate the ideal Otto cycle. Thus far, similar approaches such as Homogeneous Charge Compression Ignition (HCCI) shared the same objective yet were unable to be operated under high load conditions. Highly increased control efforts and excessive mechanical stress on the components are but a few examples of the drawbacks associated with HCCI. The approach employed in this work is the so-called Spark Assisted Compression Ignition (SACI) in combination with a pre-chamber spark plug, enabling short combustion durations even at high dilution levels. This operation mode leads to substantial improvements in terms of fuel consumption up to highest load conditions. Developed in close collaboration with Volkswagen Motorsport and the FKFS, the experimental…
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Trimmed Body Static Stiffness Identification Using Dynamic Measurements: Test Methodology and Correlation with CAE Results

Volkswagen AG-Elmar Teipen
Siemens Industry Software-Simona Anna Ottaiano, Theo Geluk
Published 2018-06-13 by SAE International in United States
A key metric of a car body structure is the body stiffness, which shows significant correlation with different vehicle performance attributes as NVH, comfort and vehicle handling.Typical approaches to identify static stiffness characteristics are the use of a static stiffness test bench or the ‘static-from-dynamic’ approach in which free-free acquired transfer functions are used to build a modal model from which the static stiffness characteristics are extracted. Both of these approaches have limitations, the static stiffness bench with respect to clamping conditions and reproducing those in CAE, the static-from-dynamic with respect to the modal analysis (EMA) that needs to be performed. EMA is a subjective process, which can limit result robustness. In addition, performing EMA on a trimmed body is difficult due to the high modal density and the high level of damping. Strong benefit however of the static-from-dynamic approach is the ability to characterize the body stiffness without need for clamping of the structure.In this paper a robust static-from-dynamic approach is described that allows static stiffness identification not only for Body-in-White but also on…
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Steering Feedback Perception of Average Drivers

Volkswagen AG-Johannes Grau, Bastian Boßdorf-Zimmer
Institute of Automotive Engineering-Jan Hendrik Sterthoff, Roman Henze, Ferit Küçükay
Published 2018-04-15 by SAE International in United States
Electromechanical steering systems (EPS) provide assisting steering force through an electric motor, often paired with a screw drive. The combination of an electric motor and a screw drive lead to high inertia and thus to a reduced feedback of tire force behavior at the steering wheel. This force behavior contains information about driving conditions and road surface. However, the electric motor can be used to actively enhance and manipulate steering feedback. This article describes the driver perception of modified steering feedback. The presented data is collected carrying out a driving simulator study with average drivers as test subjects. In this study the driver experiences a modified steering feedback at a change of road friction coefficient. Based on the test subjects ratings the perception, acceptance and controllability of the presented steering feedback modifications are assessed. Aim of this article is to present the objectivization of subjective ratings and to describe the applicability of modified steering feedback.
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Validating Prototype Connected Vehicle-to-Infrastructure Safety Applications in Real- World Settings

Volkswagen AG-Jan-Niklas Meier
CAMP LLC-Jayendra Parikh
Published 2018-04-03 by SAE International in United States
This paper summarizes the validation of prototype vehicle-to-infrastructure (V2I) safety applications based on Dedicated Short Range Communications (DSRC) in the United States under a cooperative agreement between the Crash Avoidance Metrics Partners LLC (CAMP) and the Federal Highway Administration (FHWA). After consideration of a number of V2I safety applications, Red Light Violation Warning (RLVW), Curve Speed Warning (CSW) and Reduced Speed Zone Warning with Lane Closure Warning (RSZW/LC) were developed, validated and demonstrated using seven different vehicles (six passenger vehicles and one Class 8 truck) leveraging DSRC-based messages from a Road Side Unit (RSU). The developed V2I safety applications were validated for more than 20 distinct scenarios and over 100 test runs using both light- and heavy-duty vehicles over a period of seven months. Subsequently, additional on-road testing of CSW on public roads and RSZW/LC in live work zones were conducted in Southeast Michigan. Application performance analysis revealed that proper and accurate infrastructure maps are crucial for the desired functioning of the V2I safety applications.
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Development of Wireless Message for Vehicle-to-Infrastructure Safety Applications

Volkswagen AG-Jan-Niklas Meier
CAMP LLC-Jayendra Parikh
Published 2018-04-03 by SAE International in United States
This paper summarizes the development of a wireless message from infrastructure-to-vehicle (I2V) for safety applications based on Dedicated Short-Range Communications (DSRC) under a cooperative agreement between the Crash Avoidance Metrics Partners LLC (CAMP) and the Federal Highway Administration (FHWA). During the development of the Curve Speed Warning (CSW) and Reduced Speed Zone Warning with Lane Closure (RSZW/LC) safety applications [1], the Basic Information Message (BIM) was developed to wirelessly transmit infrastructure-centric information. The Traveler Information Message (TIM) structure, as described in the SAE J2735, provides a mechanism for the infrastructure to issue and display in-vehicle signage of various types of advisory and road sign information. This approach, though effective in communicating traffic advisories, is limited by the type of information that can be broadcast from infrastructures. The new BIM provides additional infrastructure data needed to support dynamic vehicles based safety applications and also leverages existing SAE J2735 data elements. By including data containers specific to other applications, the proposed BIM framework can be extended to support additional safety applications without compromising on backward compatibility to…
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Worldwide Electrical Energy Consumption of Various HVAC Systems in BEVs and Their Thermal Management and Assessment

Volkswagen AG-Malte Westerloh, Sven Twenhövel
University of Braunschweig-Juergen Koehler, Walter Schumacher
Published 2018-04-03 by SAE International in United States
Battery electric vehicles (BEVs) are equipped with Mobile Air Conditioning systems (MACs) to ensure a comfortable cabin temperature in all climates and ambient conditions as well as the optional conditioning of the traction battery. An assessment of the global electrical energy consumption of various MACs has been derived, where the basis of the assessment procedure is the climate data GREEN-MAC-LCCP 2007 (Global Refrigerants Energy & Environmental - Mobile Air Condition - Life Cycle Climate Performance) and the improved LCCP2013 (Life Cycle Climate Performance. The percentage driving time during 6 AM and 24 PM is divided into six different temperature bins with the solar radiation and relative humidity for 211 cities distributed over Europe, North, Central, and South America, Asia, South West Pacific, and Africa. The energy consumption of the MACs is determined by a thermal vehicle simulation. In this work, four different MACs are simulated and compared. The MACs that are investigated are two conventional refrigeration cycles with PTC (Positive Thermal Coefficient, one with R-1234yf and the other with R-744 as the refrigerant, as well…
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Open Access

In-Cylinder LIF Imaging, IR-Absorption Point Measurements, and a CFD Simulation to Evaluate Mixture Formation in a CNG-Fueled Engine

SAE International Journal of Engines

Volkswagen AG-Peter Kawelke, Julian Luciani, Lars Beckmann, Jasper Zachow
LaVision GmbH-Manuel Schuette, Olaf Thiele, Thomas Berg
  • Journal Article
  • 2018-01-0633
Published 2018-04-03 by SAE International in United States
Two optical techniques were developed and combined with a CFD simulation to obtain spatio-temporally resolved information on air/fuel mixing in the cylinder of a methane-fueled, fired, optically accessible engine. Laser-induced fluorescence (LIF) of anisole (methoxybenzene), vaporized in trace amounts into the gaseous fuel upstream of the injector, was captured by a two-camera system, providing one instantaneous image of the air/fuel ratio per cycle. Broadband infrared (IR) absorption by the methane fuel itself was measured in a small probe volume via a spark-plug integrated sensor, yielding time-resolved quasi-point information at kHz-rates. The simulation was based on the Reynolds-averaged Navier-Stokes (RANS) approach with the two-equation k-epsilon turbulence model in a finite volume discretization scheme and included the port-fuel injection event. Commercial CFD software was used to perform engine simulations close to the experimental conditions. Experimentally, the local gas temperature influences both LIF and IR measurements through the photophysics of fluorescence and IR absorption, respectively. Thus, in advances over previous implementations, both techniques also measured temperature and used this information to improve the accuracy of the measured air/fuel…
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The Thermodynamics of Exhaust Gas Condensation

SAE International Journal of Engines

Volkswagen AG-Nuria Garrido Gonzalez, Jens Drueckhammer, Christoph Kaeppner
Technische Universitat Berlin-Roland Baar
  • Journal Article
  • 2017-01-9281
Published 2017-06-29 by SAE International in United States
Water vapor is, aside from carbon dioxide, the major fossil fuel combustion by-product. Depending on its concentration in the exhaust gas mixture as well as on the exhaust gas pressure, its condensation temperature can be derived. For typical gasoline engine stoichiometric operating conditions, the water vapor dew point lies at about 53 °C. The exhaust gas mixture does however contain some pollutants coming from the fuel, engine oil, and charge air, which can react with the water vapor and affect the condensation process. For instance, sulfur trioxide present in the exhaust, reacts with water vapor forming sulfuric acid. This acid builds a binary system with water vapor, which presents a dew point often above 100 °C.Exhaust composition after leaving the combustion chamber strongly depends on fuel type, engine concept and operation point. Furthermore, the exhaust undergoes several chemical after treatments. The transformation of pollutants in these components drastically affects the composition of the possible exhaust condensate, which can for instance shift its pH-value from acidic to alkaline.Detailed analysis of these condensable exhaust components and understanding…
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Analysis of Cycle-to-Cycle Variations of the Mixing Process in a Direct Injection Spark Ignition Engine Using Scale-Resolving Simulations

SAE International Journal of Engines

Volkswagen AG-Karsten Michels, Martin Hofer
FVTR GmbH-Martin Theile
  • Journal Article
  • 2016-01-9048
Published 2016-11-16 by SAE International in United States
Since the mechanisms leading to cyclic combustion variabilities in direct injection gasoline engines are still poorly understood, advanced computational studies are necessary to be able to predict, analyze and optimize the complete engine process from aerodynamics to mixing, ignition, combustion and heat transfer. In this work the Scale-Adaptive Simulation (SAS) turbulence model is used in combination with a parameterized lagrangian spray model for the purpose of predicting transient in-cylinder cold flow, injection and mixture formation in a gasoline engine. An existing CFD model based on FLUENT v15.0 [1] has been extended with a spray description using the FLUENT Discrete Phase Model (DPM). This article will first discuss the validation of the in-cylinder cold flow model using experimental data measured within an optically accessible engine by High Speed Particle Image Velocimetry (HS-PIV). Afterwards, the parameterized spray model is validated using experimental data measured in a pressure spray chamber. Finally, results obtained with the combined model are discussed and used to analyze transient mixture formation and to give a detailed insight into cycle-to-cycle fluctuations associated with the…
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