Non-premixed laminar or turbulent flames can undergo extinction when scalar dissipation rates exceed a critical value. When local extinction occurs, negative edge flames that act to expand the region of extinction are initially present. Steady negative edge flames have been previously studied in a combustor designed to support the negative propagation velocity of the flame edge, but unsteady negative edge flames have not received significant attention. The current study uses numerical simulations in a simple flowfield to produce unsteady negative edge flames which oscillate in response to imposed strain rate fluctuations in order to understand the dynamic response of extinction edge propagation. An energy balance through the edge shows that the unsteady behavior can be well described by a simple extension of the energy balance from steady flames. Furthermore, the edge velocity was calculated, and a physical interpretation of the extinction velocity was derived using the energy budget. The time scale of the imposed strain rate fluctuations was varied to show a limited response time for the extinction edge flame dynamics.
|Number of pages||11|
|Journal||Combustion and Flame|
|State||Published - May 2020|
Bibliographical noteFunding Information:
This material is based upon work supported by the National Science Foundation under Grant no. CBET-1552074 . The authors would like to thank Dr. Vish Katta for modifying UNICORN for these simulations.
© 2020 The Combustion Institute
- Edge flame dynamics
- Laminar flames
- Negative edge flames
ASJC Scopus subject areas
- Chemistry (all)
- Chemical Engineering (all)
- Fuel Technology
- Energy Engineering and Power Technology
- Physics and Astronomy (all)