Detonation Propagation in Mixtures Undergoing Autoignition and Deflagration

Detonations in rotating detonation engines do not achieve the wave velocities predicted by the Chapman-Jouguet model. One potential cause is autoignition and deflagration of the fresh reactants ahead of the detonation wave due to contact with and mixing with the exhaust products of the previous wave. The burning of fuel ahead of the wave reduces the amount of energy available to the detonation wave. An experiment was designed to study this phenomenon by inducing autoignition and deflagration ahead of a detonation wave in an optically accessible channel to measure the velocity decrement of the wave. The results showed that the velocities increased as the channel was filled with more hot exhaust, and that for some cases, autoignition occurred ahead of the detonation wave.