A 2-D DNS investigation of extinction and reignition dynamics in nonpremixed flame-vortex interactions

Journal Article · Thu May 15 00:00:00 EDT 2008 · Combustion and Flame

DOI:https://doi.org/10.1016/J.COMBUSTFLAME.2007.10.021· OSTI ID:21036813

Venugopal, Rishikesh; Abraham, John ^[1]

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1. Maurice J. Zucrow Laboratories, School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907-2088 (United States)

Two-dimensional (2-D) DNS investigations of extinction and reignition dynamics during interactions of laminar nonpremixed flames with counterrotating vortex pairs are performed. The length and velocity scales chosen for the vortices are representative of those in the near fields of high-Reynolds-number jets such as those occurring in Diesel engines. The governing equations are solved with sixth-order spatial discretization and fourth-order time integration. Chemistry is modeled as an irreversible single-step reaction. Local extinction along the symmetry axis, followed by reignition, is observed. The extinction is characterized by strong unsteady effects, which are captured well by 1-D transient diffusion flamelet libraries, provided the time-history of the instantaneous scalar dissipation rate is taken into account. On the other hand, reignition is essentially a 2-D phenomenon involving flame-flame interactions, which are favored for smaller vortices and increasing flame curvature. The effects of unsteadiness and curvature on extinction and reignition are carefully assessed through parametric studies involving a range of vortex and flame characteristics. The interaction outcomes are summarized on Reynolds-Damkoehler number (Re-Da) diagrams, which show the combined effects of unsteadiness and curvature on extinction and reignition. The implications of the observed interaction outcomes for turbulent combustion modeling in the near fields of jet diffusion flames are discussed. (author)

• OSTI ID: 21036813
• Journal Information: Combustion and Flame, Journal Name: Combustion and Flame Journal Issue: 3 Vol. 153; ISSN CBFMAO; ISSN 0010-2180
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
COMBUSTION
COMPUTERIZED SIMULATION
Curvature
DIAGRAMS
DIESEL ENGINES
DIFFUSION
EQUATIONS
FLAME EXTINCTION
Flame-vortex interactions
IGNITION
JETS
LAMINAR FLAMES
PARAMETRIC ANALYSIS
Reignition
TWO-DIMENSIONAL CALCULATIONS
Unsteadiness
VORTICES