Accession Number : ADA310467

Title :   A Theory of DDT in Unconfined Flames.

Corporate Author : NAVAL RESEARCH LAB WASHINGTON DC SENIOR SCIENTIST FOR REACTIVE FLOW PHYSICS

Personal Author(s) : Khokhlov, Alexei M. ; Oran, Elaine S. ; Wheeler, J. C.

PDF Url : ADA310467

Report Date : 19 JUN 1996

Pagination or Media Count : 27

Abstract : 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.

Descriptors :   *FLAME PROPAGATION, *DETONATIONS, *DEFLAGRATION, SHOCK WAVES, TURBULENCE, TURBULENT FLOW, FUEL AIR RATIO, EULER EQUATIONS, COMBUSTION STABILITY, BURNING RATE, LAMINAR FLOW, ENTROPY, SPONTANEOUS COMBUSTION, JET MIXING FLOW, DETONATION WAVES, REACTIVE GASES, JET FLAMES.

Subject Categories : Combustion and Ignition

Distribution Statement : APPROVED FOR PUBLIC RELEASE