Flame propagation along the vortex axis

• The problem of how to include fast burning along the vortex axis into the general description of turbulent flames is discussed. It is shown that, from such a point of view, the most representative geometry of the flow is burning in a hypothetic 'tube' with rotating gaseous mixture. Direct numerical simulations of flame propagation in the hypothetic tube are performed on the basis of the complete system of hydrodynamic equations, including thermal conduction, diffusion, viscosity and chemical kinetics written in the rotational reference frame. The geometry of an axisymmetric flame front is studied, which allows reducing the dimension of the problem by one, thus saving computational time. The numerical results are analysed using the ideas of bubble rising in the acceleration field created by the centrifugal force. It is shown that the velocity of flame propagation is determined mostly by the velocity of bubble rising when the frequency of the tube rotation is sufficiently large. When the rotational frequency is moderate, then the velocity of flame propagation is determined by the planar flame velocity, by the hydrodynamic flame instability and by the gas rotation. Calculations given in the present paper are in agreement with the previous theoretical and experimental results.

Nyckelord

Premixed flame

Turbulent vortex

Hydrodynamic instability

Bubble rising

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