Flow Topology of Three-Dimensional Spherical Flame in Shock Accelerated Flows

Abstract EN

The flow topologies of compressible large-scale distorted flames are studied by means of the analysis of the invariants of the velocity gradient tensor (VGT).

The results indicate that compressibility plays a minor role in the distorted flame zone.

And the joint probability density function (p.d.f.) of the Q - R diagram appears as a teardrop shape, which is a universal feature of turbulence.

Therefore, the distorted flame exhibits the characteristic of large-scale turbulence combustion, especially behind the reflected shock wave, while the p.d.f.

of the Q S ⁎ - Q W diagram implies that the dissipation is enhanced in the compression and expansion regions, where it is higher than that when P = 0 .

Furthermore, we identify that the flame evolution is dominated by rotation by means of a quantitative statistical study, and the SFS topology is the predominant flow pattern.

Not surprisingly, negative dilatation could suppress the unstable topologies, whereas positive dilatation could suppress the stable topologies.