Detonation Waves and Propulsion

The possibility of using a detonation wave as the key combustion system for supersonic propulsion is examined. A brief review of propagating detonations is provided first. This review emphasizes the unique and unstable nature of the coupling between reaction zone and shock waves that characterize detonations. The theory of idealized, steady, oblique detonation waves and their reaction zone structure are summarized. The evidence for the existence of stabilized or steady oblique detonations is discussed. Experiments with multiple layers of explosive and projectiles fired into explosive gases are examined. There are a variety of reasons that these previous studies have failed to produce stabilized detonations. A brief catalog of difficulties is provided and based on analogies with our knowledge of propagating detonations, a set of criteria are proposed for the existence and stability of stabilized detonations. The problems of initiation and instability are examined for the situation of a flow over a wedge.