A Theory of DDT in Unconfined Flames.
NAVAL RESEARCH LAB WASHINGTON DC SENIOR SCIENTIST FOR REACTIVE FLOW PHYSICS
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This paper outlines a theoretical approach for predicting the onset of detonation in unconfined turbulent flames. Two basic assumptions are made 1 the gradient mechanism is the inherent mechanism that leads to DDT in unconfined conditions, and 2 the sole mechanism for preparing the gradient in induction time is by turbulent mixing and local flame quenching. The criterion for DDT is derived in terms of the one-dimensional detonation wave thickness, the laminar flame speed, and the laminar flame thickness in the reactive gas. This approach gives a lower-bound criterion for DDT for conditions where shock preheating, wall effects, and interactions with obstacles are absent. Regions in parameter space where unconfined DDT can and cannot occur are determined.
- Combustion and Ignition