On adiabatic stabilization of inverted flames

The possibility that an inverted flame can be stabilized without heat loss to the stabilizing rod was explored by first experimentally demonstrating that there indeed exist situations under which heat loss to the stabilizing rod was negligible, especially near the state of blowoff. A theory on adiabatic flame stabilization was then proposed, in which the dynamic balance between the flame and flow velocities at the flame base is achieved through active modification of the flame speed by the combined stretch effects of flame curvature and of aerodynamic straining imposed by the rear stagnation flow field downstream of the rod. The analysis identifies (1) the existence of stabilization regimes respectively dominated by flame curvature and by flow straining, and the characteristics of the associated flame responses; (2) the existence of stable and unstable branches of the solution; (3) the importance of the mixture Lewis number which is characteristic of stretched flame phenomena; and (4) a rational blowoff criterion of adiabatically stabilized flames. Further experimental observations support such behavior. Implications on flame stablization and blowoff in other situations including the Bunsen flame are discussed.