The influence of shear layer control on DDT

An investigation into the shear layer control of impulsive jets was carried out by comparing of different types of nozzles that were used as injectors in detonation experiments. High-speed schlieren images of the non-reactive air flow from a supersonic nozzle, a whistler nozzle and a sonic generator captured the evolution of the flow features and allowed the acoustic wave frequency to be determined. The contact surface area was calculated for the injectors. Under the same initial conditions, the contact surface areas from the different configurations are strongly different. Different injectors were mounted in turn to the injector block of a detonation tube. The flame front, shock, detonation and retonation waves were observed via pressure transducers and photodetectors. A detonation wave was observed at equivalence ratios of 0.5–2.3 for whistler and supersonic nozzles but not for sonic generators within a distance of less than 4 tube diameters.