Abstract

This study provides a macroscopic, experimental analysis of the impact of turbulence on the dynamics of a detonation wave. The interaction of detonation waves with turbulence is widely encountered in detonation-based propulsion devices such as the rotating detonation engine (RDE), and a good understanding of this interaction is needed for suitable orifice design and wave stability and sustainability. In this study, experiments were conducted in a detonation tube with multiple inlets. One inlet is used to slowly fill the tube with a reactive mixture, while the other is used for the rapid injection of a jet into an initially quiescent medium, thereby generating turbulence. Detonation waves are initiated from one end of the tube using a high power ignition system. A schlieren visualization system is used to capture images as blasts and detonation waves pass through an optical viewing section at the other end of the tube. Five levels of turbulence were generated for each fill pressure of 10 kPa, 20 kPa, and 30 kPa. Detonation speeds were measured from the captured images and compared to those of detonations propagating in a quiescent medium at the same pressures. It was found that turbulence enhances the propagation of detonations with larger cell size (at 10 kPa) bringing its speed closer to the ideal, Chapman-Jouguet, detonation speed, and hinders the propagation of detonations with smaller cells (at 20 kPa and 30 kPa) increasing the deficit below the wave’s CJ speed at the given pressure. This result implies that there exists a critical cell size, characteristic of the reactive mixture, at which a switch in behaviour occurs under the influence of turbulence. Consequently, a minimum cell size must be attained, in order to recover lost energy of a detonation wave and use turbulence favourably.