Abstract
Turbulent eddies in an ethylene jet flame are visualized by a laser-light sheet method. Tracer particles are soot spontaneously formed in the interface between fuel and air. The observation of the eddies in the flame shows that the scale of eddies in the flame increases with the kinematic viscosity so that the dissipation into smaller eddies is inhibited. It is also shown that large eddies in the horizontal cross section fold up the flame boundaries and make soot layers stretch thinner, thereby promoting air entrainment and fuel-air mixing. The eddies in the horizontal plane exhibit greater influence than the coherent ones in the shear layer. In addition, a hot and viscous soot layer formed in the outer region keeps the turbulent eddies from mixing with surrounding air, resulting in complicated, random patterns in the vicinity of the break point.
