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Diel, Hartmut
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Investigation of Flame Propagation Description in Quasi-Dimensional Spark Ignition Engine Modeling

Audi AG-Ulrich Baretzky, Hartmut Diel, Sebastian Wohlgemuth, Gordon Röttger
FKFS-Michael Grill
Published 2018-09-10 by SAE International in United States
The engine development process has been enhanced significantly by virtual engineering methods during the last decades. In terms of in-cylinder flow field, charge flow and combustion modelling, 3D-CFD (three dimensional) simulations enable detailed analysis and extended investigations in order to gain additional knowledge about design parameters. However, the computational time of the 3D-CFD is an obvious drawback that prevents a reasonable application for extensive analysis with varying speed, load and transient conditions. State-of-the-art 0D (zero dimensional) approaches close the gap between the demand of high computational efficiency and a satisfying accordance with experimental data. Recent improvements of phenomenological combustion approaches for gasoline spark ignition engines deal with the consideration of detailed flow parameters, the accuracy of the laminar flame speed calculation and the prediction of the knock limit. Little attention has been given to the influence of different combustion chamber designs on the prediction capability so far. This leads to an often used simplification consisting of a combustion chamber modeled as a disk and an acceptable inaccuracy of combustion modelling. With an increasing deviation of…
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Virtual Optimization of Race Engines Through an Extended Quasi Steady State Lap Time Simulation Approach

AUDI AG-Ulrich Baretzky, Hartmut Diel, Sebastian Wohlgemuth
FKFS-Michael Grill
Published 2018-04-03 by SAE International in United States
Minimizing the lap time for a given race track is the main target in racecar development. In order to achieve the highest possible performance of the vehicle configuration the mutual interaction at the level of assemblies and components requires a balance between the advantages and disadvantages for each design decision. Especially the major shift in the focus of racecar powerunit development to high efficiency powertrains is driving a development of lean boosted and rightsized engines. In terms of dynamic engine behavior the time delay from requested to provided torque could influence the lap time performance. Therefore, solely maximizing the full load behavior objective is insufficient to achieve minimal lap time.By means of continuous predictive virtual methods throughout the whole development process, the influence on lap time by dynamic power lags, e.g. caused by the boost system, can be recognized efficiently even in the early concept phase. As a first step, this paper presents a novel method that combines detailed 1D (one dimensional) gas dynamic engine models with the quasi steady state (QSS) lap time method.…
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The Direct Injection System of the 2001 Audi Turbo V8 Le Mans Engines

AUDI AG-Ulrich Baretzky, Tomas Andor, Hartmut Diel, Wolfgang Ullrich
Published 2002-12-02 by SAE International in United States
Audi's successful 3.6 L V8 twin turbo Le Mans engine of 2000 has been developed to fuel direct injection (FSI®). Most of the modifications have been done in the area of the cylinderhead. Simulation and flow test bench work helped to define the basic parameters. The FSI® engine has a reduction in fuel consumption of 8 - 10 %, up to 9 % more torque throughout the entire speed range and much better driveability.
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