Year-end Sale % OFF 
Abstract
Premixed flame propagation in obstructed channels with both extremes open is studied by means of computational simulations of the reacting flow equations with a fully-compressible hydrodynamics, transport properties (heat conduction, diffusion and viscosity) and an Arrhenius chemical kinetics. The aim of this paper is to distinguish and scrutinize various regimes of flame propagation in this configuration depending on the geometrical and thermal-chemical parameters. The parametric study includes various channel widths, blockage ratios, and thermal expansion ratios. It is found that the interplay of these three critical parameters determines a regime of flame propagation. Specifically, either a flame propagates quasi-steady, without acceleration, or it experiences three consecutive distinctive phases (quasi-steady propagation, acceleration and saturation). This study is mainly focused on the flame acceleration regime. The accelerating phase is exponential in nature, which correlates well with the theoretical prediction from the literature. The accelerating trend also qualitatively resembles that from semi-open channels, but acceleration is substantially weaker when both extremes are open. Likewise, the identified regime of quasi-steady propagation fits the regime of flame oscillations, found for the low Reynolds number flames. In addition, the machine learning logistic regression algorithm is employed to characterize and differentiate the parametric domains of accelerating and non-accelerating flames.
Highlights
IntroductionA flame is ignited at the closed end and propagates towards the open extreme), with evenly arranged and closely packed obstacles along the sidewalls, have been reported to experience ultrafast premixed flame acceleration (FA) and eventually an event of deflagration-to-detonation transition (DDT) [1,2,3,4,5]
Semi-open channels and tubes, with evenly arranged and closely packed obstacles along the sidewalls, have been reported to experience ultrafast premixed flame acceleration (FA) and eventually an event of deflagration-to-detonation transition (DDT) [1,2,3,4,5]
The research methodology employed here is based on scrutinizing reacting flows in fully-open, obstructed channels by means of computational simulations of the governing partial differential equations (PDE) for a conservation/balance of mass, momentum, energy and species, including a equations (PDE) for a conservation/balance of mass, momentum, energy and species, including a fully-compressible hydrodynamics, transport properties, and an Arrhenius chemical kinetics represented by a one-step irreversible reaction of the first order
Summary
A flame is ignited at the closed end and propagates towards the open extreme), with evenly arranged and closely packed obstacles along the sidewalls, have been reported to experience ultrafast premixed flame acceleration (FA) and eventually an event of deflagration-to-detonation transition (DDT) [1,2,3,4,5] This acceleration mechanism is conceptually laminar, being devoted to a powerful jet flow along the pipe centerline [1]. Industrial and laboratory conduits oftentimes have both extremes open, which attracted the interest for decades, starting with the classical experimental works on chocked flames [6] and quasi-detonations [7] in open obstructed pipes; see [8,9] and references therein for details. Non-restriction of the flow in axial direction results in a mechanism of flame propagation different from that previously
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
