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Optimizing engine concepts by using a simple model for knock prediction
KTH, Superseded Departments, Machine Design.
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
KTH, Superseded Departments, Machine Design.
Show others and affiliations
2003 (English)In: SAE Paper 2003-01-3123, SAE , 2003Conference paper, Published paper (Refereed)
Abstract [en]

The objective of this paper is to present a simulation model for controlling combustion phasing in order to avoid knock in turbocharged SI engines. An empirically based knock model was integrated in a one-dimensional simulation tool. The empirical knock model was optimized and validated against engine tests for a variety of speeds and λ . This model can be used to optimize control strategies as well as design of new engine concepts.

Place, publisher, year, edition, pages
SAE , 2003.
Series
SAE Technical Paper Series, ISSN 0148-7191
National Category
Other Materials Engineering
Identifiers
URN: urn:nbn:se:kth:diva-6543DOI: 10.4271/2003-01-3123OAI: oai:DiVA.org:kth-6543DiVA: diva2:11284
Conference
SAE Powertrain & Fluid Systems Conference & Exhibition, October 2003, Pittsburgh, PA, USA
Note
QC 20101111Available from: 2006-12-11 Created: 2006-12-11 Last updated: 2010-12-09Bibliographically approved
In thesis
1. 1-D simulation of turbocharged SI engines: focusing on a new gas exchange system and knock prediction
Open this publication in new window or tab >>1-D simulation of turbocharged SI engines: focusing on a new gas exchange system and knock prediction
2006 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

This licentiate thesis concerns one dimensional flow simulation of turbocharged spark ignited engines. The objective has been to contribute to the improvement of turbocharged SI engines’ performance as well as 1 D simulation capabilities.

Turbocharged engines suffer from poor gas exchange due to the high exhaust pressure created by the turbine. This results in power loss as well as high levels of residual gas, which makes the engine more prone to knock.

This thesis presents an alternative gas exchange concept, with the aim of removing the high exhaust pressure during the critical periods. This is done by splitting the two exhaust ports into two separate exhaust manifolds.

The alternative gas exchange study was performed by measurements as well as 1-D simulations. The link between measurements and simulations is very strong, and will be discussed in this thesis.

As mentioned, turbocharged engines are prone to knock. Hence, finding a method to model knock in 1-D engine simulations would improve the simulation capabilities. In this thesis a 0-D knock model, coupled to the 1-D engine model, is presented

Place, publisher, year, edition, pages
Stockholm: KTH, 2006. viii, 51 p.
Series
Trita-MMK, ISSN 1400-1179 ; 2006:14
Keyword
spark ignited engines, 1-D flow simulation, knock, Divided Exhaust Period, turbocharged engines
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:kth:diva-4218 (URN)
Presentation
2006-12-15, Sal M3, KTH, Brinellvägen 64, Stockholm, 10:00
Opponent
Supervisors
Note
QC 20101112Available from: 2006-12-11 Created: 2006-12-11 Last updated: 2010-11-12Bibliographically approved
2. Empirical combustion modeling in SI engines
Open this publication in new window or tab >>Empirical combustion modeling in SI engines
2005 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

This licentiate thesis concerns the modeling of spark ignition engine combustion for use in one dimensional simulation tools. Modeling of knock is of particular interest when modeling turbocharged engines since knock usually limits the possible engine output at high load. The knocking sound is an acoustic phenomenon with pressure oscillations triggered by autoignition of the unburned charge ahead of the propagating flame front and it is potentially damaging to the engine. To be able to predict knock it is essential to predict the temperature and pressure in the unburned charge ahead of the flame front. Hence, an adequate combustion model is needed.

The combustion model presented here is based on established correlations of laminar burning velocity which are used to predict changes in combustion duration relative to a base operating condition. Turbulence influence is captured in empirical correlations to the engine operating parameters spark advance and engine speed. This approach makes the combustion model predictive in terms of changes in gas properties such as mixture strength, residual gas content, pressure and temperature. However, a base operating condition and calibration of the turbulence correlations is still needed when using this combustion model.

The empirical models presented in this thesis are based on extensive measurements on a turbocharged four cylinder passenger car engine. The knock model is simply a calibration of the Arrhenius type equation for ignition delay in the widely used Livengood-Wu knock integral to the particular fuel and engine used in this work.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005. xii, 72 p.
Series
Trita-MMK, ISSN 1400-1179 ; 2005:19
Keyword
spark ignited engines, combustion modeling, knock, 1D simulation, Wiebe, divided exhaust period
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-575 (URN)
Presentation
2005-09-26, B1, KTH, Brinellvägen 23, Stockholm, 13:00
Note
QC 20101209Available from: 2005-12-28 Created: 2005-12-28 Last updated: 2010-12-09Bibliographically approved

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