Further insight into the gas flame acceleration mechanisms in pipes. Part II: Numerical work

• Published in: Journal of loss prevention in the process industries Vol. 62; p. 103919
• Main Authors: Lecocq, Guillaume, Leprette, Emmanuel, Daubech, Jérôme, Proust, Christophe
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.11.2019; Elsevier
• Subjects: CFD; Environmental Engineering; Environmental Sciences; Methane; Pipe; Premixed flame; Methane; CFD; Premixed flame; Pipe; PREMIXED FLAME; METHANE; PIPE
• ISSN: 0950-4230
• DOI: 10.1016/j.jlp.2019.103919

This paper is the second part of a global study investigating the physics of premixed flame propagation in several kinds of long pipes. It focuses on the potential of CFD for modelling such cases. Four tests among the database detailed in the first part are selected. In each case, the pipe is straight, open at one end and closed at the other where ignition is triggered. The pipe is filled with a stoichiometric methane/air mixture at rest. The parameters which are varied are the inner pipe diameter and the pipe material. CFD computations based on a URANS framework are carried out and enable to recover several physical trends, such as the role of acoustics and boundary layer turbulence on the flame dynamics. Although most orders of magnitude of the measured overpressure peaks can be predicted numerically, the computed flames are quicker than the measured ones. It could be explained by the chosen turbulent model, the k-ω SST model, known to be adapted for wall-bounded flows but to produce too much turbulence for accelerating flows. The criterion for the cells size near wall (y+<200) might also be too loose. •Specific physics of the flame propagation in semi-open tube was qualitatively recovered by CFD.•CFD could approach the flame propagation history in PMMA tubes neglecting the effect of turbulence.•The k-omega SST model seems to overestimate turbulence production for an accelerating flow.