The influence of confinement on the propagation of near limit detonation waves /

This thesis reports on a detailed experimental investigation of near limit ethylene-air detonation phenomena in tubes. The different detonation regimes were determined as a function of ignition energy, composition and stability for a specific tube diameter. The dependence of single head spin detonations on the tube diameter was further investigated. This study has revealed that the different near limit regimes are governed by the acoustic coupling with the tube walls and can be influenced by the energy of the ignition source. The effective source energy and the distance over which this energy will support a detonation phenomenon have been quantified.It has been shown that the characteristic detonation cell size of the mixture can be obtained by matching the cell length to the spin pitch of the mixture in which the single head spin phenomenon is first observed. In addition, a model for predicting the detonation cell sizes as a function of composition is presented. The detonability limit in a tube has been defined as the composition for onset of spin in this tube. The cell size correlation was effectively used in order to predict the critical tube diameters and minimum ignition energies for unconfined situations