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Large Eddy Simulations and Tracer-LIF Diagnostics of Wall Film Dynamics in an Optically Accessible GDI Research Engine

Robert Bosch GmbH-Jan N. Geiler, Andreas Manz
ETH Zurich-Nicolò Frapolli, Konstantinos Boulouchos, Yuri M. Wright
Published 2019-09-09 by SAE International in United States
Large Eddy Simulations (LES) and tracer-based Laser-Induced Fluorescence (LIF) measurements were performed to study the dynamics of fuel wall-films on the piston top of an optically accessible, four-valve pent-roof GDI research engine for a total of eight operating conditions. Starting from a reference point, the systematic variations include changes in engine speed (600; 1,200 and 2,000 RPM) and load (1000 and 500 mbar intake pressure); concerning the fuel path the Start Of Injection (SOI=360°, 390° and 420° CA after gas exchange TDC) as well as the injection pressure (10, 20 and 35 MPa) were varied. For each condition, 40 experimental images were acquired phase-locked at 10° CA intervals after SOI, showing the wall-film dynamics in terms of spatial extent, thickness and temperature. The simulation framework was developed as follows: first, the spray model was calibrated using spray morphology evolution data of the same injector, characterized in a constant volume spray chamber by high-speed shadow imaging. In a second step, the wall impingement and film models were calibrated using the reference condition. With the model constants…
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Analyze This! Sound Static Analysis for Integration Verification of Large-Scale Automotive Software

Robert Bosch GmbH-Bernard Schmidt, Maximilian Schlund
Absint Angewandte Informatik Gmbh-Daniel Kaestner, Laurent Mauborgne, Stephan Wilhelm, Christian Ferdinand
Published 2019-04-02 by SAE International in United States
Safety-critical embedded software has to satisfy stringent quality requirements. One such requirement, imposed by all contemporary safety standards, is that no critical run-time errors must occur. Runtime errors can be caused by undefined or unspecified behavior of the programming language; examples are buffer overflows or data races. They may cause erroneous or erratic behavior, induce system failures, and constitute security vulnerabilities. A sound static analyzer reports all such defects in the code, or proves their absence. Sound static program analysis is a verification technique recommended by ISO/FDIS 26262 for software unit verification and for the verification of software integration. In this article we propose an analysis methodology that has been implemented with the static analyzer Astrée. It supports quick turn-around times and gives highly precise whole-program results. We give an overview of the key concepts of Astrée that enable it to efficiently handle large-scale code, and describe a pre-analysis which transforms the source code to make it better amenable to static analysis. The experimental results confirm that sound static analysis can be successfully applied for…
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Loss of Control Car Accidents on Indian Roads - Benefit Estimation of ESC

Robert Bosch GmbH-Joerg Moennich, Thomas Lich, Andreas Georgi
Robert Bosch Engineering and Business Solutions Pvt Ltd-Girikumar Kumaresh
Published 2019-01-09 by SAE International in United States
India has one of the highest growth rates of individual mobility in the world, as well as one of the largest numbers of road casualties. Modern active safety systems are slowly becoming established in the Indian passenger car market. The intension of this study is to investigate the effectiveness of the car safety feature Electronic Stability Control (ESC) for India. The Indian accidents has to be analysed to identify the reliable root cause. For this purpose, passenger car Loss of Control accidents were investigated in more detail with the aim of estimating the safety potential of ESC for India. A methodology is developed to extrapolate the in-depth accident database of Road Accident Sampling System for India (RASSI) to the entire accident situation in India. Loss of Control accidents are analysed with regard to their root causes, crash consequences and contributing factors. The initial findings of the study reveals that the accident scenario Loss of Control of cars is significantly prominent in India. The analysis shows that about 40,000 Loss of Control car accidents with injury…
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Comprehensive Study on Crashes with Pedestrians on Indian Roads

Robert Bosch GmbH-Moennich Joerg, Thomas Lich
Robert Bosch Engineering and Business Solutions Pvt Ltd-Girikumar Kumaresh
Published 2019-01-09 by SAE International in United States
Pedestrian crashes are a major safety concern worldwide, especially in India. About one of every ten traffic-related fatalities in the country is a pedestrian. In 2016 nearly 15,800 pedestrians were killed in India. They were mainly exposed to risk when crossing and walking on the road in urban and rural areas. The aim of the study was to understand the pedestrian behavior on the road and to identify characteristics of pedestrian crashes in India. Many unique behavior was observed like pedestrian crossed half way and stopped in middle of road. Nearly 10% of pedestrians are fatal each year involving in ~5% of overall accidents in India, This study revels every second pedestrian accident occurred while walking and crossing the road straight. An attempt made to evaluate benefit of in vehicle pedestrian safety systems, as an example Car-AEB (Advance Emergency Braking) pedestrian is selected as one of the available technologies and systematic methodology is derived in order to evaluate the benefit of this product.
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Model Guided Application for Investigating Particle Number (PN) Emissions in GDI Spark Ignition Engines

SAE International Journal of Advances and Current Practices in Mobility

Robert Bosch GmbH-Andreas Manz, Jan Niklas Geiler
CMCL Innovations-Kok Foong Lee, David Ooi, Jiawei Lai, Amit Bhave
  • Journal Article
  • 2019-26-0062
Published 2019-01-09 by SAE International in United States
Model guided application (MGA) combining physico-chemical internal combustion engine simulation with advanced analytics offers a robust framework to develop and test particle number (PN) emissions reduction strategies. The digital engineering workflow presented in this paper integrates the kinetics & SRM Engine Suite with parameter estimation techniques applicable to the simulation of particle formation and dynamics in gasoline direct injection (GDI) spark ignition (SI) engines. The evolution of the particle population characteristics at engine-out and through the sampling system is investigated. The particle population balance model is extended beyond soot to include sulphates and soluble organic fractions (SOF). This particle model is coupled with the gas phase chemistry precursors and is solved using a sectional method. The combustion chamber is divided into a wall zone and a bulk zone and the fuel impingement on the cylinder wall is simulated. The wall zone is responsible for resolving the distribution of equivalence ratios near the wall, a factor that is essential to account for the formation of soot in GDI SI engines. In this work, a stochastic reactor…
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Water Load Determination Approach in Two Wheeler Exhaust System

Robert Bosch GmbH-Andrea Krusch, Konrad Meister, Christopher Holzknecht
Bosch Limited-Ranjana Kumari Meena
Published 2018-10-30 by SAE International in United States
Future emission norms in India (BS6) necessitates the 2 wheeler industry to work towards emission optimization measures. Engine operation at stoichiometric Air-Fuel Ratio (AFR) would result in a good performance, durability and least emissions. To keep the AFR close to stoichiometric condition, an Oxygen sensor is placed in the exhaust system, which detects if air-fuel mixture is rich (λ<1) or lean (λ>1) and provides feedback to fuel injection system for suitable fuel control.O2 sensor has a ceramic element, which needs to be heated to a working temperature for its functioning. The ceramic element would break (thermal shock) if water in liquid form comes in contact with it when the element is hot. To counter this, oxygen sensor is either fully heated only when all the water in the exhaust system is evaporated, which results in delayed closed loop control, or is capable to withstand higher amount of water in the exhaust system by for example being applied with thermal shock protection and a protective tube. It’s a challenge to control the HC emissions during first…
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Investigation on the Transient Behavior of a Two-Wheeler Single Cylinder Engine Close to Idling with Electronic Throttle Control

Robert Bosch GmbH-Henning Heikes, Alexander Pelkmann, Alrik Barton
Published 2018-10-30 by SAE International in United States
The introduction of new emission legislation and the demand of increased power for small two-wheelers lead to an increase of technical requirements. Especially for single cylinder engines with high compression ratio the transient behavior close to idling is challenging.The demand for two-wheeler specific responsiveness of the vehicle requires low overall rotational inertia as well as small intake manifold volumes. The combination with high compression ratio can lead to a stalling of the engine if the throttle opens and closes very quickly in idle operation. The fast opening and closing of the throttle is called a throttle blip. Fast, in this context, means that the blipping event can occur in one to two working cycles.Previous work was focused on the development of a procedure to apply reproducible blipping events to a vehicle in order to derive a deeper physical understanding of the stalling events. The corresponding investigations were performed on a motorcycle with a mechanical throttle body. Based on this the present paper is focused on a comparison to a motorcycle with the same base engine…
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A Review of the Requirements for Injection Systems and the Effects of Fuel Quality on Particulate Emissions from GDI Engines

Robert Bosch GmbH-Tobias Knorsch, Christoph Laidig, Wolfram Wiese
University of Oxford-Felix Leach
Published 2018-09-10 by SAE International in United States
Particulate emissions from Gasoline Direct Injection (GDI) engines have been an important topic of recent research interest due to their known environmental effects. This review paper will characterise the influence of different gasoline direct injection fuel systems on particle number (PN) emissions. The findings will be reviewed for engine and vehicle measurements with appropriate driving cycles (especially real driving cycles) to evaluate effects of the fuel injection systems on PN emissions. Recent technological developments alongside the trends of the influence of system pressure and nozzle design on injector tip wetting and deposits will be considered. Besides the engine and fuel system it is known that fuel composition will have an important effect on GDI engine PN emissions. The evaporation qualities of fuels have a substantial influence on mixture preparation, as does the composition of the fuel itself. Recently a number of studies have attempted to link fuel composition with PN emissions, developing a variety of indices including the PM index (Aikawa et al.) and the PN index (Leach et al.). An extensive literature search has…
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Experimental Investigation of Flame-Wall-Impingement and Near-Wall Combustion on the Piston Temperature of a Diesel Engine Using Instantaneous Surface Temperature Measurements

Robert Bosch GmbH-Daniel Mayer, Alexander Seelig, Torsten Kunz, Fabian Kopple, Matthias Mansbart
IVK, University of Stuttgart-Michael Bargende
Published 2018-09-10 by SAE International in United States
The heat transfer process in a reciprocating engine is dominated by forced convection, which is drastically affected by mean flow, turbulence, flame propagation and its impingement on the combustion chamber walls. All these effects contribute to a transient heat flux, resulting in a fast-changing temporal and spatial temperature distribution at the surface of the combustion chamber walls.To quantify these changes in combustion chamber surface temperature, surface temperature measurements on the piston of a single cylinder diesel engine were taken. Therefore, thirteen fast-response thermocouples were installed in the piston surface. A wireless microwave telemetry system was used for data transmission out of the moving piston.A wide range of parameter studies were performed to determine the varying influences on the surface temperature of the piston. For instance, at later injection timings a shift of the peak temperature towards later crank angles with an immediately decreasing surface temperature increase can be measured. Higher engine speeds increase the mean piston temperature, while the local surface temperature increase during combustion decreases. At higher intake pressures and therefore higher gas densities,…
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Locally Structured Fiber Reinforcements: An Approach to Realize Anisotropic Directivity Pattern in Ultrasound Transducers

Robert Bosch GmbH-Johannes Henneberg, André Gerlach
Technical University Chemnitz-Holger Cebulla
Published 2018-06-13 by SAE International in United States
Ultrasonic transducers are widely used in automotive and industrial applications for surround sensing. Anisotropic directivity patterns with a narrow-angled beam in the vertical plane and a wide-angled beam in the horizontal plane are needed in automotive applications particularly. Today’s ultrasonic transducers for automotive applications are mainly metal based, pot-like ultrasonic transducers. The anisotropic directivity pattern is achieved by increasing the thickness of the vibrating plate-like part of the structure locally. Composites with locally structured fiber reinforcements open up the possibility to design the dynamical behavior of components without changing its contour. Using this new dimension of design to modify the directivity pattern of sound radiating components is less examined in literature. In this work, the possibility of creating an anisotropic directivity pattern by locally structuring the fiber reinforcement is investigated using a generic ultrasonic transducer model. The structuring is realized by sections of carbon fiber reinforced epoxy and sections made of epoxy only. Furthermore, the influence of geometrical and material uncertainties of the fiber reinforcement on the directivity pattern is discussed. The authors identify locally…
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