Numerical simulations of interactions between a flame bubble with an incident shock wave and its focusing wave

Abstract

The numerical investigations of interactions between a flame bubble with an incident shock wave (IW) and its focusing wave (FW) in a reactive CH 4 -O 2 -N 2 mixture are presented. The time-dependent, two-dimensional axisymmetric, reactive Navier-Stokes equations, with detailed chemical mechanisms, are employed to simulate the multiple shock-flame interactions process. The effects of the IW Mach number and chemical reactivity of mixture on flame structure and evolution are examined. The results of simulations show that the initial flame bubble can interact with IW, bow wave (BW), reflected BW, and FW in sequence. For the weak IW case, the repeated shock-flame interactions produce multiple Richtmyer-Meshkov (RM) instabilities that lead to the convolved flame with vortex structures, and the chemical heat release does not play a major role. While for the strong IW case, the multiple RM instabilities lead to the highly distorted flame with the complex vortices structures of large magnitude. With the lower reactive mixture, the instability process is the major mechanism for shock-flame interaction, while the chemistry only plays a minor role. However, with the higher reactive mixture, the distorted flame expands rapidly and finally forms the large-scale combustion through the interaction with FW. Both instability and chemical heat release play the important mechanisms in this case. The combustion acceleration in the highly reactive mixture can produce the stronger overpressure and the higher propagation speed of complex FW because of the chemi-acoustic interaction effect.

Three-Dimensional Numerical Modeling of a Coastal Highway Bridge under Stokes Waves

“…Some studies have neglected the effect of bridge flexibility, and some have considered it in their calculations in different ways. Many studies have been done on the bridge superstructure with rigid support under wave loads [6,15,17,[22][23][24]. e bridge deck with flexible support is a problem that has not been adequately studied yet.…”

“…e bridge deck with flexible support is a problem that has not been adequately studied yet. Today, powerful software packages are made by computers that can analyze fluid-solid interaction (FSI) problems accurately, but using them to analyze any problem requires verification with similar laboratory models [23]. As an experimental work that considered deck flexibility, we can mention Bradner et al ey made one span of the I-10 Bridge over Escambia Bay with a 1: 5 scale in the Oregon State University wave flume.…”

An incremental-stencil WENO reconstruction for simulation of compressible two-phase flows

“…The problems of compressible two-phase flow present in many research fields, such as aero-and astronautics, mechanics, material science, astrophysics, nuclear engineering even medical sciences. Several typical examples are underwater explosion, biomedical ultrasound and shock wave lithotripsy [1,2] and shock-induced mixing of liquid fuel droplets in scramjet combustor [3], etc. The related researches are valuable from both theoretical and application points of view.…”

Linear analysis of the Richtmyer-Meshkov instability in shock-flame interactions

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