J. Yanez

Parameterization of Laminar Burning Velocity Dependence on Pressure and Temperature in Hydrogen/Air/Steam Mixtures

A new correlation describing the laminar burning velocity of hydrogen/air mixtures as a function of temperature, pressure, and mixture composition is proposed. The correlation is developed for reactive hydrogen/air mixtures diluted with steam for wide temperature, pressure, and composition ranges. The study includes the following stages: first, the laminar burning velocity was calculated with the detailed reaction mechanism of Maas and Warnatz (1988) implemented in the code INSFLA; second, the results obtained were validated against experimental data and a new heuristic approximation based on them was created. The correlation found consists of simple mathematical expressions and provides a good approximation of the laminar burning velocity in the range between 200 K and 600 K for temperature, between 0.1 bar and 10 bar for pressure, and up to 20 mol% steam dilution.

Flame Acceleration and DDT in a Torus Geometry

A series of combustion experiments in an optically transparent annular channel were carried out with hydrogenoxygen mixtures from 15 to 85 vol.% H2. The complex formed by an oblique shock wave and a subsonic deflagration, only recently observed by the authors in an annular channel is investigated. The ensemble has the notable property of propagating with the Chapman-Jouguet velocity up to 3000 m/s in the circumferential direction being of intrinsic subsonic nature. The structure is discussed in detail utilizing an algebraic approach to provide an insight of the apparently contradictory experimental observation of a deflagration which propagates with its Chapman-Jouguet velocity.