Flame propagation and acoustics

An intense effect of acoustic waves on the structure and shape of the burner flame was discovered by Rayleigh. The present paper deals with acoustic waves in the case of flame propagation in a tube. The flame emits acoustic waves generating the flow in the tube. Being actually a wave beam, the flow bounded by the walls experiences friction and also diffraction divergence, resulting in the emergence of secondary waves, i.e., waves of flow perturbations. They induce the formation of a cellular structure of the flame; at high velocities, the flame becomes turbulent. All these processes play important roles in the deflagration-to-detonation transition in tubes. Emission of acoustic waves by the flame is also responsible for the formation of spherical detonation. Spin and pulsed detonation can be interpreted on the same basis.