Explosions caused by the high-speed combustion and deflagration-to-detonation transition (DDT) in reactive gases present a significant hazard to a variety of industrial and energy-related applications. For example, hydrogen fuel, which used in fuel cells, internal combustion engines, and other devices, is particularly sensitive to detonation. A better understanding of DDT would help improve safety for hydrogen gas handling, storage, and transport. Nuclear reactors are another technology that is susceptible to catastrophic detonation events. Their extensive networks of long residual heat-removal pipes lend themselves to flame acceleration and DDT.

To date, a complete first-principles understanding of DDT is lacking. Researchers will address this issue by using the DOE’s leadership-class supercomputers to perform a systematic numerical study of high-speed deflagration, DDT, and resulting detonation waves. This will help scientists understand the mechanisms responsible for DDT in various gaseous mixtures, including hydrogen-oxygen mixtures, syngas, and ethylene (one of the most widely used hydrocarbons in chemical industries).

The proposed study requires first-principles, reactive flow Navier-Stokes direct numerical simulations (DNS), which explicitly resolve physical processes on spatial scales ranging from the size of the combustion device to the micron scales associated with viscosity, heat conduction, and mass diffusion. The DNS also consider relevant chemical reactions, interaction of the flame with turbulence, sound and shock waves, boundary layers, and the development and autoignition of hot spots.

These simulations, which were not practical without the power of petascale computing, will produce findings that inform risk-reduction strategies and improve safety for hydrogen fuel use, nuclear reactors, and many other industrial settings.