Mechanism of Flame Propagation along a Vortex Tube

Abstract

Vortex tubes are recognized as sinews of turbulence: The length of the vortex tube represents the integral scale of turbulence, the spacing of the nodes of the vortex tube represents the Taylor micro scale, and the diameter of the vortex tube represents the 10 times the Kolmogorov scale (Tanahashi and Miyauchi, 1999). Thus the interaction between a fine vortex tube and a flame seems to be an essential process in turbulent combustion. The aim of this work is to study the mechanism of flame propagation along a fine vortex tube of a premixed gas when the vortex tube interacts perpendicularly with the flame (Chomiak, 1976). It is well known that a premixed flame propagates rapidly with a velocity similar to the maximum circumferential velocity of the vortex core. It is also known that the premixed flame can propagate along the vortex tube when the maximum circumferential velocity is faster than the burning velocity and the core diameter is larger than the flame thickness (Hasegawa et al., 1995). However, the mechanism of the flame propagation is still not clear though several models have been proposed. In this study, the flame propagation along a fine vortex tube is numerically simulated and the mechanism that provokes the flame to propagate along the vortex tube is discussed in terms of the vorticity transport equation.