Journal Article

A unified mechanism for unconfined deflagration-to-detonation transition in terrestrial chemical systems and type Ia supernovae

Gamezo, Vadim N., Taylor, Brian D., Chambers, Jessica, Poludnenko, Alexei Y., Ahmed, Kareem

2019

Overview

In some forms of supernovae and chemical explosions, a flame moving at subsonic speeds (deflagration) spontaneously evolves into one driven by a supersonic shock (detonation), vastly increasing the power output. The mechanism of this deflagration-to-detonation transition (DDT) is poorly understood. Poludnenko et al. developed an analytical model to describe DDTs, then tested it with lab experiments and numerical simulations. Their model successfully reproduced the DDT seen in the experiments and predicted a DDT in type Ia supernovae, which is consistent with observational constraints. The same mechanism may apply to DDTs in any unconfined explosion. Science , this issue p. eaau7365 A detonation formation model is developed for chemical flames and supernovae by using lab experiments and numerical simulations. The nature of type Ia supernovae (SNIa)—thermonuclear explosions of white dwarf stars—is an open question in astrophysics. Virtually all existing theoretical models of normal, bright SNIa require the explosion to produce a detonation in order to consume all of stellar material, but the mechanism for the deflagration-to-detonation transition (DDT) remains unclear. We present a unified theory of turbulence-induced DDT that describes the mechanism and conditions for initiating detonation both in unconfined chemical and thermonuclear explosions. The model is validated by using experiments with chemical flames and numerical simulations of thermonuclear flames. We use the developed theory to determine criteria for detonation initiation in the single-degenerate Chandrasekhar-mass SNIa model and show that DDT is almost inevitable at densities of 10 7 to 10 8 grams per cubic centimeter.

• Publisher: American Association for the Advancement of Science,The American Association for the Advancement of Science
• Subject: Aerodynamics / Astrophysics / Burning / Burning rate / Chemical explosions / Coal mines / Coal mining / Combustion / Computational fluid dynamics / Computer simulation / Deflagration / Detonation waves / Experiments / Explosions / First principles / Industrial plants / Laboratory Experiments / Mathematical models / Mining / Nuclear electric power generation / Nuclear energy / Nuclear fuels / Organic chemistry / Reacting flow / RESEARCH ARTICLE SUMMARY / Simulation / Stars / Subsonic aircraft / Supernovae / Terrestrial environments / Theory / Thermonuclear explosions / Turbulence / Turbulent flames / White dwarf stars / White dwarfs