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Modeling Tire Tread Features

SAE International Journal of Passenger Cars - Mechanical Systems

Chalmers University of Technology, Sweden-Michael D.P. Bolzon
  • Journal Article
  • 06-13-01-0001
Published 2020-01-09 by SAE International in United States
This study details an investigation into the accuracy of a recently proposed tire rotation simulation approach, termed the “MRFg” method. Physical experiments and computational fluid dynamics (CFD) simulations were conducted on a sedan-type passenger vehicle with various tire treads and rims. Furthermore, the effects of the wind tunnel geometry on the method’s accuracy was investigated. The experimental data consisted of drag coefficients, front and rear lift coefficients, base and door surface pressures, and wake surveys at various planes around the wheels. Overall, a comprehensive set of validation data was taken. The CFD simulations were transient, and the geometry closely replicated the experimental geometry, including the tires’ deformations. Generally, the MRFg method predicted the effects of the various tread patterns on the drag coefficient to within four counts. Some outliers occurred. The MRFg method predicted some of the flowfield trends and magnitudes very well, but not others. The inclusion of the wind tunnel geometry significantly increased the accuracy of the methodology.
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Energy-Efficient Cooperative Adaptive Cruise Control with Receding Horizon of Traffic, Route Topology, and Traffic Light Information

SAE International Journal of Connected and Automated Vehicles

Chalmers University of Technology, Sweden-Anders Grauers
Chalmers University of Technology, Sweden AVL List GmbH, Austria-Niklas Wikström
  • Journal Article
  • 12-02-02-0006
Published 2019-05-16 by SAE International in United States
Advanced and cooperative vehicle (semi-) autonomous driving systems will become a necessity in the future for sustainable, convenient, and safe mobility. By utilizing Vehicle-to-Vehicle (V2V) and Vehicle-to-Infrastructure (V2I) communication, a vehicle’s energy consumption can be reduced while maintaining safety and driving comfort. A holistic control strategy is presented, which in a novel way incorporates traffic lights, road speed limits, gradients, and curvature, as well as surrounding traffic and detailed powertrain characteristics into a single Model Predictive Control formulation. The performance of the system is evaluated using a realistic co-simulation toolchain representing the vehicle, driver, and road, including complex traffic conditions. The approach is valid for a wide range of scenarios, ranging from urban city driving to highways. Simulation results for a D-class passenger car with a diesel engine and an automatic transmission in an urban route show energy savings between 5% and 30% with an unchanged travel time, compared to a simulated human driver.
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Industrial Framework for Identification and Verification of Hot Spots in Automotive Composite Structures

SAE International Journal of Materials and Manufacturing

Chalmers University of Technology, Sweden-Leif E. Asp
Volvo Car Corporation, Sweden-Henrik Molker, Renaud Gutkin
  • Journal Article
  • 05-12-02-0009
Published 2019-05-16 by SAE International in United States
In this article, a framework for efficient strength analysis of large and complex automotive composite structures is presented. This article focuses on processes and methods that are compliant with common practice in the automotive industry. The proposed framework uses efficient shell models for identification of hot spots, automated remodelling and analysis of found hot spots with high-fidelity models and finally an automated way of post-processing the detailed models. The process is developed to allow verification of a large number of load cases in large models and still consider all potential failure modes. The process is focused on laminated composite primary structures. This article highlights the challenges and tools for setting up this framework.
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Role of Piston Bowl Shape to Enhance Late-Cycle Soot Oxidation in Low-Swirl Diesel Combustion

SAE International Journal of Engines

Chalmers University of Technology, Sweden-Jan Eismark, Mats Andersson, Anders Karlsson, Ingemar Denbratt
AB Volvo, Sweden-Magnus Christensen
  • Journal Article
  • 03-12-03-0017
Published 2019-04-25 by SAE International in United States
Late-cycle soot oxidation in heavy-duty (HD) diesel engine low-swirl combustion was investigated using single-cylinder engine and spray chamber experiments together with engine combustion simulations. The in-cylinder flow during interactions between adjacent flames (flame-flame events) was shown to have a large impact on late-cycle combustion. To modify the flame-flame, a new piston bowl shape with a protrusion (wave) was designed to guide the near-wall flow. This design significantly reduced soot emissions and increased engine thermodynamic efficiency. The wave’s main effect was to enhance late-cycle mixing, as demonstrated by apparent rate of heat release after the termination of fuel injection. Combustion simulations showed that the increased mixing is driven by enhanced flow re-circulation, which produces a radial mixing zone (RMZ). The leading edge of the RMZ extends toward the center of the piston bowl, where unused ambient gas is available, promoting oxidation. The wave also enhances mixing in the trailing edge of the RMZ when it detaches from the wall, accelerating the burn-out of the RMZ. This flame interaction effect was isolated and studied further using a…
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Stratified Cold Start Sprays of Gasoline-Ethanol Blends

SAE International Journal of Fuels and Lubricants

Chalmers University of Technology, Sweden-Stina Hemdal, Ingemar Denbratt, Petter Dahlander
General Motors Powertrain, Sweden-Jonas Warnberg
  • Journal Article
  • 2009-01-1496
Published 2009-04-20 by SAE International in United States
Gasoline and gasoline-ethanol sprays from an outward-opening piezo-injector were studied in a constant volume/pressure chamber using high-speed imaging and phase doppler anemometry (PDA) under stratified cold start conditions corresponding to a vehicle ambient temperature of 243 K (−30°C/−22°F); in-cylinder air pressure of 5 bar, air temperature of 350 K (−30°C/−22°F) and fuel temperature of 243 K. The effects of varying in-cylinder pressure and temperature, fuel injection pressure and fuel temperature on the formation of gasoline, E75 and pure ethanol sprays were investigated. The results indicate that fuel composition affects spray behaviour, but less than expected. Furthermore, varying the temperature of the fuel or the air surrounding the spray also had minor effects. As expected, the fuel injection pressure was found to have the strongest influence on spray formation under stratified conditions.
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Survey of Past, Present and Planned Human Space Mission Simulators

Chalmers University of Technology, Sweden-Susmita Mohanty
Architecture & Vision, Germany-Andreas Vogler
Published 2008-06-29 by SAE International in United States
In light of the renewed international interest in lunar exploration, including plans for setting up a permanent human outpost on the Moon, the need for next generation earth-based human space mission simulators has become inevitable and urgent. These simulators have been shown to be of great value for medical, physiological, psychological, biological and exobiological research, and for subsystem test and development, particularly closed-loop life support systems.The paper presents a summary of a survey of past, present and future human space mission simulators. In 2006, the Vienna based company Liquifer Systems Group (LSG) conducted an in-depth survey, for a European Space Agency (ESA) commissioned Phase-A contract involving a Design Study for a Facility for Integrated Planetary Exploration Simulation (FIPES). The survey data served as reference material for development of the FIPES architecture and, more importantly the application of the data ensured that the Systems Requirements reviewed and amended as part of the FIPES Study fully reflected the design, experience, and lessons learned from the use of such facilities.The paper addresses a hitherto unfulfilled need: a comprehensive,…
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Three-Dimensional Simulation of Diesel Spray Ignition and Flame Lift-Off Using OpenFOAM and KIVA-3V CFD Codes

Chalmers University of Technology, Sweden-Fabian Peng Kärrholm, Feng Tao
Scania CV, Sweden-Niklas Nordin
Published 2008-04-14 by SAE International in United States
Three-dimensional simulations of ignition and combustion of a diesel spray were conducted. The primary goal of the work was to compare two different CFD codes: OpenFOAM, an object-oriented C++ based code, and KIVA-3V. The spray is modelled by the Eulerian-Lagrangian approach in both codes, with several common submodels. Some important sub-models implemented include inter alia a Kelvin-Helmholtz/Rayleigh-Taylor (KH/RT) model for spray break-up, an improved spray collision model, and a Partially Stirred Reactor (PaSR) model for turbulence-chemistry interaction. Both CFD codes solve the chemical reaction equations in a fully coupled manner. A cubic-shaped Cartesian mesh was used in the KIVA-3V simulations, while a polyhedral mesh including a combination of hexagonal and prism-shaped cells was constructed for the OpenFOAM computations.The effects of high EGR and ambient temperature on the ignition and flame lift-off processes of a diesel spray were investigated. Sandia experiments conducted in a high-pressure and high-temperature constant-volume vessel were chosen for the simulations and validations. A single spray was injected into the vessel, and EGR was mimicked by reducing the oxygen concentration. The diesel reference…
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A LIF-study of OH in the Negative Valve Overlap of a Spark-assisted HCCI Combustion Engine

Chalmers University of Technology, Sweden-Andreas W. Berntsson, Mats Andersson, Daniel Dahl, Ingemar Denbratt
Published 2008-04-14 by SAE International in United States
Future requirements for emission reduction from combustion engines in ground vehicles might be met by using the HCCI combustion concept. In this study, negative valve overlap (NVO) and low lift, short duration, camshaft profiles, were used to initiate HCCI combustion by increasing the internal exhaust gas recirculation (EGR) and thus retaining sufficient thermal energy for chemical reactions to occur when a pilot injection was introduced prior to TDC, during the NVO.One of the crucial parameters to control in HCCI combustion is the combustion phasing and one way of doing this is to vary the relative ratio of fuel injected in pilot and main injections. The combustion phasing is also influenced by the total amount of fuel supplied to the engine, the combustion phasing is thus affected when the load is changed. This study focuses on the reactions that occur in the highly diluted environment during the NVO when load and pilot to main ratio are changed.To monitor these reactions, planar laser-induced fluorescence (PLIF) from OH radicals was analyzed in a series of experiments with an…
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Evaluation of a Closed Loop Spark Advance Controller Based on a Torque Sensor

SAE International Journal of Passenger Cars - Electronic and Electrical Systems

Chalmers University of Technology, Sweden-Ingemar Andersson, Thomas McKelvey, Mikael Thor
  • Journal Article
  • 2008-01-0987
Published 2008-04-14 by SAE International in United States
A closed loop spark advance control system was evaluated on a Volvo V70 5-cylinder spark ignited engine. The system utilises a crankshaft mounted torque sensor for combustion monitoring which provides individual cylinder combustion phasing information and enables individual cylinder spark advance control. The spark advance control system can compensate for changes in combustion operating conditions and hence limit the need for calibration.The spark advance control system was used in a mode of cylinder balancing where the control target is to keep the combustion phasing in all cylinders at a defined setpoint. This control law was evaluated in vehicle tests in an emission test chamber, running pre-defined driving cycles FTP72 and Highway Fuel Economy Test. Analysis shows that the combustion phasing was kept close to the selected setpoint during both tests and, hence, robustness in that sense was demonstrated.The torque ratio concept is used for combustion phasing monitoring based on crankshaft torque measurements. Analysis of the 50% torque ratio as a measure for combustion phasing shows that it is equivalent to 50% burned mass fraction.
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Optical study of HCCI Combustion using NVO and an SI Stratified Charge

Chalmers University of Technology, Sweden-Andreas W. Berntsson, Ingemar Denbratt
Published 2007-09-16 by Consiglio Nazionale delle Ricerche in Italy
The effects of using an SI stratified charge in combination with HCCI combustion on combustion phasing, rate of heat release and emissions were investigated in engine experiments to identify ways to extend the operational range of HCCI combustion to lower loads.In the experiments an optical single-cylinder engine equipped with a piezo electric outward-opening injector and operated with negative valve overlap (NVO) and low lift, short duration, camshaft profiles, was used to initiate HCCI combustion by increasing the exhaust gas recirculation (EGR) and thus retaining sufficient thermal energy to reach auto-ignition temperatures.Two series of experiments with full factorial designs were performed, to investigate how the tested parameters (amounts of fuel injected in pilot injections and main injections, stratification injection timing and spark-assistance) influenced the combustion.In the optical study fourth harmonic light (266 nm) from a Nd:YAG laser was used to induce fluorescence (LIF), from 3-pentanone added as a fuel tracer, to analyze the concentration and distribution of fuel vapor within the cylinder. In addition third harmonic light (355 nm) was used to study the concentration and…
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