A Study of Two Basic Issues Relevant to RANS Simulations of Stratified Turbulent Combustion in a Spray-Guided Direct-Injection Spark-Ignition Engine
Journal article, 2014

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

Author

Chen Huang

Chalmers, Applied Mechanics, Combustion

Andrei Lipatnikov

Chalmers, Applied Mechanics, Combustion

Lars Christian Riis Johansen

Chalmers, Applied Mechanics, Combustion

Stina Hemdal

Chalmers, Applied Mechanics, Combustion

SAE Technical Papers

0148-7191 (ISSN)

2014-01-2572 1-15

Areas of Advance

Transport

Energy

Subject Categories

Energy Engineering

Fluid Mechanics and Acoustics

Roots

Basic sciences

DOI

10.4271/2014-01-2572

More information

Created

10/7/2017