Dynamics of water droplets in a counterflow field and their effect on flame extinction

Journal Article · Thu Oct 01 04:00:00 EDT 1998 · Combustion and Flame

DOI:https://doi.org/10.1016/S0010-2180(97)00355-6· OSTI ID:669951

Lentati, A M; Chelliah, H K ^[1]

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1. Univ. of Virginia, Charlottesville, VA (United States). Dept. of Mechanical, Aerospace and Nuclear Engineering

The effect of fine-water droplets in extinguishing steady, laminar counterflow methane-air nonpremixed flames is investigated here, using a numerical approach. A new two-phase model using a hybrid Eulerian-Lagrangian formulation for the gas-droplet flow is developed as part of this work. A key feature of the model developed is that it can avoid the singularity associated with the droplet number density equation in a consistent manner by using a Lagrangian equation for droplet flux fraction. The gas phase is described by a detailed model involving full chemical kinetics and transport, whereas droplet evaporation and heat transfer are modeled assuming quasisteady conditions. Application of the model to several monodisperse sizes of water droplets, ranging from 5--50 {micro}m, revealed an interesting nonmonotonic dependence of the flame extinction strain rate on droplet size. This phenomenon is attributed to the droplet dynamics in the counterflow field considered here and to the resulting nonmonotonic heat sink associated with mass evaporation observed at the oxygen-consumption or radical production layer of the flame.

• OSTI ID: 669951
• Journal Information: Combustion and Flame, Journal Name: Combustion and Flame Journal Issue: 1-2 Vol. 115; ISSN 0010-2180; ISSN CBFMAO
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
COMBUSTION KINETICS
DROPLETS
FIRE EXTINGUISHERS
FLAMES
INHIBITION
MATHEMATICAL MODELS
METHANE
PARTICLE SIZE
SPRAYS
WATER