Experimental study on propagation mode of H2/Air continuously rotating detonation wave

Abstract

The propagation mode of H2/Air continuously rotating detonation waves (CRDWs) has been experimentally studied in a rotating detonation engine (RDE) model which injected gaseous H2 and Air in slit-orifice collision mode. Experiments were conducted by varying injection conditions (different mass flow rates and equivalence ratio) at atmospheric backpressure, and thereby four typical detonation propagation modes were concluded. Moreover, the injection conditions, as well as the time domain and frequency domain characteristics for each mode were detailedly analyzed. Results show that: for the test model with an oxidizer injection throat of 0.4 mm wide, H2/Air CRDW usually propagated in an one-way mode as the mass flow rate increased, which in sequence included three sorts of mode: single wave mode, single/dual-wave hybrid mode, and dual-wave mode. However, after the blow-off N2 was injected and the H2 flow began to decrease, the detonation was possible to be maintained in a special dual-wave collision mode. This collision mode was more likely to be observed in the test model with a narrower oxidizer injection throat of 0.2 mm wide. At lower mass flow rate, CRDWs tended to show unstable dual-wave collision mode, and the collision points slowly moved back and forth within a small azimuthal angle; with the mass flow rate increasing, the collision points remained stable and CRDWs propagated in stable dual-wave collision mode.