Top: wavefront position along a confined tube for both regimes. Bottom: pressure profile immediately behind each front.
Industrial process-safety engineering draws a sharp line between two combustion-wave regimes: deflagration, a subsonic flame front propagating by ordinary heat conduction and diffusion into the unburned mixture ahead of it, and detonation, a supersonic wave in which the reaction zone is driven by shock compression at the Chapman-Jouguet velocity. This simulation compares both side by side in a confined tube, along with the deflagration-to-detonation transition (DDT) risk that reactivity and confinement together create — a key hazard concept in gas and dust-explosion venting design.
Two combustion wavefronts moving along a tube at very different speeds, their pressure profiles, and a DDT-risk gauge driven by fuel-air reactivity and tube confinement.
Set Fuel-Air Reactivity and Tube Confinement to see both wave speeds, pressure ratios and the DDT-risk gauge update live. Click Re-ignite to restart the animation.
Real industrial gas-explosion incidents are far more dangerous when a deflagration accelerates into a detonation partway down a confined pipe run — this is exactly why process-safety codes require careful attention to pipe length, obstacles and turbulence-inducing features, not just the initial ignition source.
Deflagration is a subsonic flame front that propagates by heat and species diffusion into the unburned mixture ahead of it. Detonation is a supersonic wave in which a shock compresses and ignites the mixture just ahead of the reaction zone, travelling at the Chapman-Jouguet velocity — fundamentally a different propagation mechanism, not just a faster version of the same one.
Confinement promotes turbulence in the flow ahead of the flame, and turbulent flame speeds run substantially faster than smooth laminar ones because the flame surface area wrinkles and increases, which is why this model scales deflagration speed up with confinement.
DDT is the process by which an initially subsonic deflagration accelerates — usually through turbulence and pressure-piling in a confined space — until it transitions into a supersonic detonation. It's one of the most safety-critical phenomena in industrial gas and dust-explosion hazard assessment.
No — it only compares two abstract combustion-wave propagation regimes using illustrative speed and pressure-ratio curves, the same conceptual content taught in industrial process-safety and gas-explosion venting engineering courses.