Mechanism of end-gas autoignition induced by flame-pressure interactions in confined space

Abstract

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Relationship of flame propagation and combustion mode transition of end-gas based on pressure wave in confined space

“…Actually, pressure waves are generated continually as the flame propagates, some of which can catch up with this strongest pressure wave and coalesce with it, but some not. Note that this strongest pressure wave dominates the reactivity increase of the end-gas [26]. As shown at 279 μs, a detonation wave is observed, induced by the end-gas autoignition.…”

“…The thermodynamics properties, transport parameters and reaction rate are evaluated by the Chemkin-II library [42] linked to AMROC. With adaptive mesh refinement method, AMROC can accurately resolve the flame front, shock wave and detonation, and thus has been successfully applied to extensive studies of flame propagation, detonation [38,[43][44][45][46][47],as well as our previous investigation of autoignition [26]. More detailed information on the governing equations and numerical methods can be found in the previous article [26] and thus is not repeated here.…”

“…The results indicate that all the grid resolutions can give reasonable evolutions of the flame and pressure waves, while the finest mesh size of 3.125 μm and 1.5625 μm can obtain a better converged solution, so the mesh size of 3.125 μm, corresponding to more than 10 cells per flame thickness and 7 cells per induction length under current initial conditions, is adopted in the present work considering the computational expenses. The same grid configuration is also used in our previous studies of autoignition and detonation development [26] and more validations of grid resolution can be found there.…”

“…However, the complexity of the three-dimensional (3D) flow and limitations of measuring means make it difficult to reveal the underlying mechanism of autoignition induced by pressure wave reflections. Thus, some numerical simulations are performed to try to provide a deeper understanding of this process [26,27]. Terashima et al [28] investigated the effects of pressure wave on hot spot formation and showed that the periodic wall reflections of the compression wave lead to the production of a larger amount of chemical species compared to that of other end-gas points.…”

Flame Propagation Dynamics in Open Tubes: Factors Influencing Combustion Conditions and Practical Implementations

“…The use of hydrogen gas (H2) has expanded the boundaries of lean flammability limitations. (25) In summary, liquefied petroleum gas (LPG) has many benefits, including increased heating value, decreased sulfur content, improved combustion cleanliness, reduced engine wear, and enhanced air-fuel mixture efficiency. Nevertheless, it is important to acknowledge that LPG does possess some limitations.…”