Browse Publications Technical Papers 2019-01-0203
2019-04-02

Effect of Turbulence-Chemistry Interaction on Spray Combustion: A Large Eddy Simulation Study 2019-01-0203

Although turbulence plays a critical role in engines operated within low temperature combustion (LTC) regime, its interaction with chemistry on auto-ignition at low-ambient-temperature and lean-oxygen conditions remains inadequately understood. Therefore, it is worthwhile taking turbulence-chemistry interaction (TCI) into consideration in LTC engine simulation by employing advanced combustion models. In the present study, large eddy simulation (LES) coupled with linear eddy model (LEM) is performed to simulate the ignition process in n-heptane spray under engine-relevant conditions, known as Spray H. With LES, more details about unsteady spray flame could be captured compared to Reynolds-averaged Navier-Stokes equations (RANS). With LEM approach, both scalar fluctuation and turbulent mixing on sub-grid level are captured, accounting for the TCI. A skeletal mechanism is adopted in this numerical simulation, including 41 species and 124 reactions. Validations is carried out and numerical results show good agreement with experimental data. It is found that, Damköhler number (Da) at the onset of high temperature reaction evidently decreases as ambient temperature and oxygen reduces. Consequently, combustion mode varies from flamelet regime to slow chemistry regime, where the competitive effect between turbulent mixing and chemistry is more evident. Besides, scalar fluctuation has promoting effect on low temperature reaction, which is responsible for the over-prediction of ignition delay in low ambient temperature/oxygen condition without consideration of TCI. Further analysis of turbulence intensity on ignition is performed by using three different turbulence intensity. Contrary to what found in premixed combustion, ignition process in spray combustion will be promoted with enhanced small scale turbulence.

SAE MOBILUS

Subscribers can view annotate, and download all of SAE's content. Learn More »

Access SAE MOBILUS »

Members save up to 18% off list price.
Login to see discount.
Special Offer: Download multiple Technical Papers each year? TechSelect is a cost-effective subscription option to select and download 12-100 full-text Technical Papers per year. Find more information here.
We also recommend:
TECHNICAL PAPER

Modeling Ignition and Premixed Combustion Including Flame Stretch Effects

2017-01-0553

View Details

TECHNICAL PAPER

Experimental and Numerical Analyses for the Characterization of the Cyclic Dispersion and Knock Occurrence in a Small-Size SI Engine

2010-32-0069

View Details

TECHNICAL PAPER

Computing Statistical Averages from Large Eddy Simulation of Spray Flames

2016-01-0585

View Details

X