Direct numerical simulation of ignition in turbulent n-heptane liquid-fuel spray jets

Journal Article · Fri Jun 15 04:00:00 EDT 2007 · Combustion and Flame

DOI:https://doi.org/10.1016/J.COMBUSTFLAME.2007.03.005· OSTI ID:20909782

Wang, Y; Rutland, C J ^[1]

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1. Department of Mechanical Engineering, University of Wisconsin-Madison, WI 53706 (United States)

Direct numerical simulation was used for fundamental studies of the ignition of turbulent n-heptane liquid-fuel spray jets. A chemistry mechanism with 33 species and 64 reactions was adopted to describe the chemical reactions. The Eulerian method is employed to solve the carrier-gas flow field and the Lagrangian method is used to track the liquid-fuel droplets. Two-way coupling interaction is considered through the exchange of mass, momentum, and energy between the carrier-gas fluid and the liquid-fuel spray. The initial carrier-gas temperature was 1500 K. Six cases were simulated with different droplet radii (from 10 to 30 {mu}m) and two initial velocities (100 and 150 m/s). From the simulations, it was found that evaporative cooling and turbulence mixing play important roles in the ignition of liquid-fuel spray jets. Ignition first occurs at the edges of the jets where the fuel mixture is lean, and the scalar dissipation rate and the vorticity magnitude are very low. For smaller droplets, ignition occurs later than for larger droplets due to increased evaporative cooling. Higher initial droplet velocity enhances turbulence mixing and evaporative cooling. For smaller droplets, higher initial droplet velocity causes the ignition to occur earlier, whereas for larger droplets, higher initial droplet velocity delays the ignition time. (author)

• OSTI ID: 20909782
• Journal Information: Combustion and Flame, Journal Name: Combustion and Flame Journal Issue: 4 Vol. 149; 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
42 ENGINEERING
CARRIERS
CHEMICAL REACTION KINETICS
COMPUTERIZED SIMULATION
DIESEL ENGINES
DIRECT INJECTION ENGINES
DROPLETS
EVAPORATION
EVAPORATIVE COOLING
GAS FLOW
GAS TURBINES
HEPTANE
IGNITION
JETS
LIQUID FUELS
MASS
MIXING
PARTICLE SIZE
SPRAYS
TEMPERATURE RANGE 1000-4000 K
TIME DEPENDENCE
TURBULENCE
VELOCITY