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A Study of Two Basic Issues Relevant to RANS Simulations of Stratified Turbulent Combustion in a Spray-Guided Direct-Injection Spark-Ignition Engine

Chen Huang (Institutionen för tillämpad mekanik, Förbränning) ; Andrei Lipatnikov (Institutionen för tillämpad mekanik, Förbränning) ; Lars Christian Riis Johansen (Institutionen för tillämpad mekanik, Förbränning) ; Stina Hemdal (Institutionen för tillämpad mekanik, Förbränning)
SAE technical paper series (0148-7191). 2014-01-2572, p. 1-15. (2014)
[Artikel, refereegranskad vetenskaplig]

A Spray-Guided (SG) Direct-Injection (DI) Spark-Ignition (SI) engine is widely recognized to be a promising technology capable for substantially reducing fuel consumption and carbon dioxide emissions. Accordingly, there is a strong need for developing models of some effects specific to stratified turbulent burning under conditions of elevated and rapidly varying pressure. Two such effects were addressed in the present work by performing unsteady three-dimensional URANS simulations of stratified turbulent combustion in a SG DISI engine. First, a simple method of evaluation equilibrium combustion temperature, implemented into the CFD code OpenFOAM ® , was improved in order to take into account the dissociation of the combustion products. Second, stratified turbulent combustion is affected by fluctuations in mixture composition. A widely used approach to modeling this effect consists of invoking a presumed Probability Density Function (PDF) for mixture fraction f . Because parameters of this PDF are determined using the first and second Favre moments of the mixture fraction field, the PDF is density-weighted. However, the canonical PDF P f is required to average certain important combustion characteristics that are straightforwardly relevant to local burning rate e.g. the laminar flame speed or the product density. In the present work, the relation between the Favre and canonical PDFs was investigated under conditions associated with burning in a SG DISI engine. Finally, the stratified turbulent combustion model which invo



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Denna post skapades 2014-10-17. Senast ändrad 2015-08-27.
CPL Pubid: 204432

 

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Institutioner (Chalmers)

Institutionen för tillämpad mekanik, Förbränning

Ämnesområden

Energi
Transport
Mekanisk energiteknik
Strömningsmekanik

Chalmers infrastruktur