Detonation Waves and Propulsion

Abstract

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 andogies 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.

An experimental investigation of the direct initiation of cylindrical detonations

“…revealed that the flow field is steady and simply translating along the cord length. The existence and stability of CJ oblique detonations is thus confirmed (Pratt et al 1991;Shepherd 1994).…”

“…In this sense, the ability to predict the critical energy for the direct initiation of a cylindrical detonation provides a first-order estimate on the critical conditions for detonation initiation by a hypervelocity projectile. Furthermore, the stability of the resulting oblique detonation initiated around a projectile is of significance to applications that seek to stabilize oblique detonation waves in propulsion applications (Pratt, Humphrey & Glenn 1991;Shepherd 1994). To date, the limited velocities of gas-gun-launched projectiles, which are of the order of the Chapman-Jouguet (CJ) detonation velocity (≈ 2 km s −1 ), has not permitted observation of steady oblique detonation waves.…”

A Virtual Test Facility for Simulating Detonation-and Shock-Induced Deformation and Fracture of Thin Flexible Shells

“…By assuming a stationary one-dimensional situation consisting of a shock and a succeeding reaction, the governing equations can be transformed into a system of ordinary differential equations depending only on the distance behind the shock front. Detailed accounts of the elaborate derivation can be found for instance in [16,19,18].…”

Resolving the shock-induced combustion by an adaptive mesh redistribution method

“…doi:10.1016/j.jcp.2006. 10.006 in aerospace science mainly being a promising combustion mechanism for hypersonic propulsion devices such as pulse detonation engine, oblique detonation wave engine, and ram accelerator [3].…”