Spontaneous Transition of Turbulent Flames to Detonations in Unconfined Media
Abstract
Deflagration-to-detonation transition (DDT) can occur in a wide variety of environments ranging from experimental and industrial systems on Earth to astrophysical thermonuclear (type Ia) supernovae explosions. Substantial progress has been made in elucidating the nature of DDT in terrestrial confined systems with walls, obstacles, etc., or with pre-existing shocks. It remains unclear, however, whether DDT can occur in unconfined media. Here we show, through first-principles direct numerical simulations (DNS) of the interaction of high-speed turbulence with premixed flames, that at sufficiently high turbulent intensities, subsonic turbulent flames in unconfined environments are inherently susceptible to DDT. The associated mechanism, based on the nonsteady evolution of flames faster than the Chapman-Jouguet deflagrations, is qualitatively different from the traditionally suggested spontaneous reaction wave model, and thus does not require the formation of distributed flames. We show that the critical turbulent flame speed predicted by this mechanism for the onset of DDT is in agreement with DNS results.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 07, 2011
- Accession Number
- ADA546371
Entities
People
- Alexei Poludnenko
- Elaine Oran
- Thomas A. Gardiner
Organizations
- United States Naval Research Laboratory