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Numerical Investigation and Experimental Comparison of ECN Spray G at Flash Boiling Conditions

AVL List GmbH-Bejoy Mandumpala Devassy, Zvonimir Petranovic, Wilfried Edelbauer
  • Technical Paper
  • 2020-01-0827
To be published on 2020-04-14 by SAE International in United States
Fuel injection is a key process influencing the performance of Gasoline Direct Injection (GDI) Engines. Injecting fuel at elevated temperature can initiate flash boiling which can lead to faster breakup, reduced penetration, and increased spray-cone angle. Thus, it impacts engine efficiency in terms of combustion quality, CO2, NOx and soot emission levels. This research deals with modelling of flash boiling process occurring in gasoline fuel injectors. The flashing mass transfer rate is modelled by the advanced Hertz-Knudsen model considering the deviation from the thermodynamic-equilibrium conditions. The effect of nucleation-site density and its variation with degree of superheat is studied. The model is validated against benchmark test cases and a substantiated comparison with experiment is achieved. It is noticed that immediately after the removal of the rupture disk, a sudden depressurization occurs at the pipe’s exit resulting in the onset of violent evaporation due to flashing which limits the pressure decrease to a value slightly below the saturation pressure. Later, the flash boiling model is applied to investigate a real-size 8-hole GDI injector from Engine Combustion…
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Potential for Emission Reduction and Fuel Economy with Micro & Mild HEV

AVL List GmbH-Franz Murr, Ernst Winklhofer, Michael Weissbaeck, Gerald Teuschl
  • Technical Paper
  • 2019-28-2504
Published 2019-11-21 by SAE International in United States
The development of modern combustion engines (spark ignition as well as compression ignition) for vehicles compliant with future oriented emission legislation (BS6, Euro VI, China 6) has introduced several technologies for improvement of both fuel efficiency as well as low emissions combustion strategies. Some of these technologies as there are high pressure multiple injection systems or sophisticated exhaust gas after treatment system imply substantial increase in test and calibration time as well as equipment cost.With the introduction of 48V systems for hybridization a cost- efficient enhancement and, partially, an even attractive alternative is now available. An overview will be given on current technologies as well as on implemented test procedures. The focus will be on solutions which have potential for the Indian market, i.e. solutions which can be implemented with moderate application effort for currently available compact and medium size cars. The possibilities of 48V technologies for fuel economy and emission reduction will be discussed. Simultaneously, tools for testing and calibration at power train testbed as well as for on-road application will be presented.Furthermore, it…
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SI Engine Combustion and Knock Modelling Using Detailed Fuel Surrogate Models and Tabulated Chemistry

AVL List GmbH-Mijo Tvrdojevic, Peter Priesching
AVL Dacolt BV-Dmitry Goryntsev, Ferry Tap
Published 2019-04-02 by SAE International in United States
In the context of today’s and future legislative requirements for NOx and soot particle emissions as well as today’s market trends for further efficiency gains in gasoline engines, computational fluid dynamics (CFD) models need to further improve their intrinsic predictive capability to fulfill OEM needs towards the future. Improving fuel chemistry modelling, knock predictions and the modelling of the interaction between the chemistry and turbulent flow are three key challenges to improve the predictivity of CFD simulations of Spark-Ignited (SI) engines. The Flamelet Generated Manifold (FGM) combustion modelling approach addresses these challenges. By using chemistry pre-tabulation technologies, today’s most detailed fuel chemistry models can be included in the CFD simulation. This allows a much more refined description of auto-ignition delays for knock as well as radical concentrations which feed into emission models, at comparable or even reduced overall CFD run-time. The FGM model has a high level of intrinsic predictive capability, as already demonstrated for many academic cases as well as for industrial burners, gas turbines and diesel engines. The application to gasoline engines has…
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Analytical Wall-Function Strategy for the Modelling of Turbulent Heat Transfer in the Automotive CFD Applications

AVL List GmbH-Sanjin Saric, Branislav Basara
AVL-AST d.o.o-Simon Gomboc
Published 2019-04-02 by SAE International in United States
In contrast to the well-established “standard” log-law wall function, the analytical wall function (AWF) as an advanced modelling approach has not been extensively used in the industrial computational fluid dynamics (CFD) applications. As the model was originally developed aiming at computations on relatively coarse meshes, potential stability issues may arise due to the pressure-gradient sensitivity if employing locally inappropriate mesh layers, typically associated with the complex geometry details. This work evaluates performance of the thermal AWF, as proposed by Suga [4], in conjunction with the main flow field computed employing the k-ζ-f turbulence model and the hybrid wall treatment (denoted as AWF-e) within the Reynolds-averaged Navier-Stokes (RANS) framework. The underlying turbulence modelling approach has been widely validated in numerous industrial applications, demonstrating capability (in terms of both accuracy and robustness) to capture near-wall transport phenomena with more fidelity compared to the standard or low-Reynolds-number variants of the k-ε turbulence model. The proposed AWF-e strategy is validated on several benchmarks, namely heated pipe, E-motor cooling jacket and IC engine flows. These flow configurations involve elevated temperature…
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Modular and Swappable 48V Battery Systems for Emerging Markets

AVL List GmbH-Paul Schiffbaenker, Nils Flagmeier
AVL Software and Functions GmbH-Jeevan Reddy Neelam
Published 2019-01-09 by SAE International in United States
Electrification globally shows promise in reducing greenhouse and noxious emissions. Although there is immense potential in such technologies penetrating across vehicle segments in the Indian market, the key lies in offering scalable, cost effective battery solutions suiting the diverse product and customer needs. This paper describes the development and possible applications of a low voltage battery system that fulfills the current needs on the Indian market. Based on real-world driving profiles the energy and power output required for the target platform are determined. Keeping in mind the Indian operating conditions, safety requirements, driving behavior, charging infrastructure, operational costs, supplier network and serviceability, technical requirements for such systems are described. Also, benchmarking data of current battery systems help to optimize the mechanical, thermal, and electrical layouts. Along with the energy storage unit, a thermal system which can accommodate both passive and active cooling for both low and high-power use-cases is proposed, which further increases flexibility. The result is a modular 48V battery system which is swappable and stackable in design to target a wide range of…
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Analysis of Regulated Pollutant Emissions and Aftertreatment Efficiency in a GTDi Engine Using Different SOI Strategies

SAE International Journal of Engines

AVL List GmbH-Daniel Campos
Universitat Politècnica de València-Vicente Bermúdez, José Manuel Luján, Hector Climent, Lian Soto
  • Journal Article
  • 03-11-03-0025
Published 2018-06-25 by SAE International in United States
In order to improve performance and minimize pollutant emissions in gasoline turbocharged direct-injection (GTDi) engines, different injection strategies and technologies are being investigated. The inclusion of exhaust gas recirculation (EGR) and the variation of the start of injection (SOI) are some of these strategies that can influence the air-to-fuel (AF) mixture formation and consequently in the combustion process and pollutant emissions. This article presents a complete study of the engine performance, pollutant emissions and aftertreatment efficiency that produces the SOI variation with a fixed EGR rate in a 4-cylinder, turbocharged, gasoline direct-injection engine with 2.0 L displacement. The equipment used in this study are TSI-EEPS for particle measurement and HORIBA MEXA 1230-PM for soot measurement being HORIBA MEXA 7100-DEGR with a heated line selector the system employed for regulated gaseous emission measurement and aftertreatment evaluation. The experimental results confirm how the use of an adequate SOI strategy is indispensable to obtain low exhaust emissions values and a balance between the different pollutants. There was found a slight reduction in brake specific fuel consumption (BSFC) with…
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Methodology and Tools to Predict GDI Injector Tip Wetting as Predecessor of Tip Sooting

AVL List GmbH-Armin Fischer, Marina Thelliez
Published 2018-04-03 by SAE International in United States
With upcoming emission regulations particle emissions for GDI engines are challenging engine and injector developers. Despite the introduction of GPFs, engine-out emission should be optimized to avoid extra cost and exhaust backpressure. Engine tests with a state of the art Miller GDI engine showed up to 200% increased particle emissions over the test duration due to injector deposit related diffusion flames. No spray altering deposits have been found inside the injector nozzle.To optimize this tip sooting behavior a tool chain is presented which involves injector multiphase simulations, a spray simulation coupled with a wallfilm model and testing. First the flow inside the injector is analyzed based on a 3D-XRay model. The next step is a Lagrangian spray simulation coupled with a wallfilm module which is used to simulate the fuel impingement on the injector tip and counter-bores. Lower injection pressures and a rounded edge at the nozzle inlet due to hydro-erosive grinding are increasing the wallfilm on the injector. The simulations are verified with measurements including high speed microscopic video analyzes of the injector tip…
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Current Findings in Measurement Technology and Measurement Methodology for RDE and Fuel Consumption for Two-Wheeler-Applications

AVL List GmbH-Roland Wanker, Hubert Friedl
Graz University of Technology-Johannes Hiesmayr, Stephan Schmidt, Stefan Hausberger, Roland Kirchberger, Christian Zinner, Patrick Filips
  • Technical Paper
  • 2017-32-0041
Published 2017-11-05 by Society of Automotive Engineers of Japan in Japan
Real world operating scenarios have a major influence on emissions and fuel consumption. To reduce climate-relevant and environmentally harmful gaseous emissions and the exploitation of fossil resources, deep understanding concerning the real drive behavior of mobile sources is needed because emissions and fuel consumption of e.g. passenger cars, operated in real world conditions, considerably differ from the officially published values which are valid for specific test cycles only [1].Due to legislative regulations by the European Commission a methodology to measure real drive emissions RDE is well approved for heavy duty vehicles and automotive applications but may not be adapted similar to two-wheeler-applications. This is due to several issues when using the state of the art portable emission measurement system PEMS that will be discussed.Hence, the aim of this paper is to present current experimental investigations in measurement technology and methodology for RDE and fuel consumption with measurement equipment that is used in automotive applications and was adapted for a motorcycle. Aside the installation and calibration, cross influences of these measurement instruments and side effects will…
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Results, Assessment and Legislative Relevance of RDE and Fuel Consumption Measurements of Two-Wheeler-Applications

AVL List GmbH-Roland Wanker, Hubert Friedl
Graz University of Technology-Johannes Hiesmayr, Stephan Schmidt, Stefan Hausberger, Roland Kirchberger, Christian Zinner, Patrick Filips
  • Technical Paper
  • 2017-32-0042
Published 2017-11-05 by Society of Automotive Engineers of Japan in Japan
The reduction of environmentally harmful gases and the ambitions to reduce the exploitation of fossil resources lead to stricter legislation for all mobile sources. Legislative development significantly affected improvements in emissions and fuel consumptions over the last years, mainly measured under laboratory conditions. But real world operating scenarios have a major influence on emissions and it is already well known that these values considerably differ from officially published figures [1]. There are regulated emissions by the European Commission by means of real driving scenarios for passenger cars. A methodology to measure real drive emissions RDE is therefore well approved for automotive applications but was not adapted for two-wheeler-applications yet [2].Hence measurements have been performed on-road and on chassis dynamometer for motorcycles with the state of the art RDE measurement equipment to be prepared for possible future legislation. The collected data led to insights into driving dynamic of motorcycles. Therefore, synthetic RDE test cycles on test rig and dynamic trip indicators are discussed to gain a better understanding of the determining influencing factors for RDE and…
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Combustion System Development of a High Performance and Fuel Efficient TGDI Engine Guided by CFD Simulation and Test

AVL List GmbH-Christian Spanner, Heribert Fuchs, Werner Schrei, Karl Weihrauch
Dongfeng Motor Corporation-Gen Chen, Wenxin Cai, Jianguang Zhou
Published 2017-10-08 by SAE International in United States
A TGDI (turbocharged gasoline direct injection) engine is developed to realize both excellent fuel economy and high dynamic performance to guarantee fun-to-drive. In order to achieve this target, it is of great importance to develop a superior combustion system for the target engine. In this study, CFD simulation analysis, steady flow test and transparent engine test investigation are extensively conducted to ensure efficient and effective design. One dimensional thermodynamic simulation is firstly conducted to optimize controlling parameters for each representative engine operating condition, and the results serve as the input and boundary condition for the subsequent Three-dimensional CFD simulation. 3D CFD simulation is carried out to guide intake port design, which is then measured and verified on steady flow test bench. CFD simulation is also conducted to gain insight into in-cylinder flow, fuel-air mixture formation and combustion, and therefore, support the design of intake port, combustion chamber and piston crown. Transparent engine study is carried out under catalyst heating, part load, and full load conditions with several injector variants. Measurement data is analyzed in terms…
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