Characteristics of rotating detonation waves in a hollow chamber with different fuel injection positions

Abstract

Ethylene-air continuous rotating detonation (CRD) was achieved in the hollow chamber with different fuel injection positions. As the injection position moved downstream, the propagation mode of CRD waves appeared in the order of single-wave mode, co-rotating two-waves mode, and lifted-single-wave mode. The axial heat release rate of the former two modes were rapid, indicating that CRD waves propagated near the ethylene orifices. Typically, for CRD wave of single-wave mode, a high peak pressure (about 0.7 MPa) led to a local backflow of propellants in the head recirculation zone. The lifted-single-wave mode was a new propagation mode where the CRD wave was ‘lifted’ from the ethylene orifices. For this mode, the CRD wave propagated with little velocity deficit (8 %) but lower peak pressure (about 0.2 MPa). Besides, the axial heat release rate was much slower in this mode, indicating that the detonation wave propagated in the unburned propellants and the intermediate products of the upstream deflagration. The achieved propagation modes were significantly affected by the ethylene injection position, which was supposed to be related to the variations of matter and energy exchanges between the main stream and the combustion products in the central recirculation zone.