Effects of pressure waves on the stability of flames propagating in tubes

Abstract

Numerical simulations were performed to study the effects of pressure waves on the evolution and stability of flames propagating in tubes. The model is the fully compressible reactive Navier-Stokes equations coupled to a calibrated one-step chemical-diffusive model for combustion in a stoichiometric hydrogen-air mixture. The numerical solution method is high order in space and time, and adaptive mesh refinement provides adequate resolution of flames, boundary layers, acoustic waves, and all of their interactions. The influence of tube length scale and aspect ratio was examined for a range of tube sizes that produce tulip flames (TFs) and series of distorted tulip flames (DTFs). The simulations show that pressure waves and acoustic properties of the tube play an important role in the flame evolution, specifically in the formation and evolution of the series of increasingly wrinkled DTFs. A time scale and pressure wave analysis of the results, combined with a linear analysis to give the growth rate of the Rayleigh-Taylor instability (RTI), shows that the RTI is a primary cause for the initiation of DTFs.

Flame quenching by crimped ribbon flame arrestor: A brief review

“…In confined regions, detonations may take place after flame acceleration and DDT, propagating with a velocity below the CJ detonation velocity. The velocity deficit can be credited to the heat and momentum losses or detonation front curve [46,82,85]. As suggested by Lee [75], the deficits are seldom larger than 15% when the detonation fails in smooth tubes.…”

“…After a weak ignition, four flame morphologies in the early stages can be distinguished in pipes/tubes [43]: (1) hemispherical flame; (2) finger-shaped flame; (3) skirt of flame front touching the sidewalls and (4) tulip flame. Xiao et al [44] found a new fifth morphology, "distorted tulip" flame, which is characterized by Rayleigh-Taylor instability driven by pressure waves [45,46]. The sketch of these morphologies is shown in Figure 5.…”

“…In practice, detonations are caused by flame accelerations unless the ignition energy is extremely high [44]. Induced by a weak ignition, a flame may accelerate and undergo various stages in a tube, which is shown in Figure 4 [46].…”

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

“…Clanet 23 studied the tulip flame phenomenon in a half-open tube and noted that the formation of the tulip flame is a manifestation of the Taylor instability driven by the deceleration of the flame tip. In recent works, [24][25][26] experimental and numerical investigations were performed to study a new flame shape, called "distorted tulip" flame (DTF), which appears after a classical tulip flame is formed. In these works, Xiao et al 25 suggested that the formation of a DTF is the result of Rayleigh-Taylor instability (RTI) driven by pressure waves generated by contact of the flame front with the sidewalls.…”

“…In recent works, [24][25][26] experimental and numerical investigations were performed to study a new flame shape, called "distorted tulip" flame (DTF), which appears after a classical tulip flame is formed. In these works, Xiao et al 25 suggested that the formation of a DTF is the result of Rayleigh-Taylor instability (RTI) driven by pressure waves generated by contact of the flame front with the sidewalls. Meanwhile, shock-flame bubble interactions in terms of Richtmyer-Meshkov Instability (RMI) are also extensively investigated.…”