Zhipeng SUN, Yue HUANG, Anjia SONG, Sijia GAO
DOI Number: XXX-YYY-ZZZ
Conference number: HiSST 2024-00166
This experimental study discusses the propagation characteristics of rotating detonation waves (RDWs) in a hollow rotating detonation combustor (HRDC) using heated air-ethylene as the working fluid. Through the combination of high-frequency pressure data and high-speed photographic images, a detailed analysis of RDW propagation under high-temperature incoming flow is conducted. Additionally, the effect of equivalence ratio on RDW stability is investigated. Stabilized RDWs were successfully achieved in the experiment at a maximum total air temperature of 711 K. For total air temperatures below 650 K, a wide range of injection equivalence ratios (1.0-1.3) allows for the attainment of stable single-wave modes. Experimental results demonstrate that under high-temperature incoming flow conditions, RDWs exhibit a significant peak pressure drop while experiencing minimal velocity loss. The color of the RDWs appears lighter and a noticeable deflagration glowing area is observed within the combustion chamber. Various modes of unstable propagation are observed in RDWs, including the coexistence of single-wave and deflagration modes, the coexistence of doublel waves and deflagration modes, as well as rapid switching between single and double waves. In a HRDC , the existence of a central reflow zone along with a substantial amount of deflagration causes fuel loss, resulting in the RDW front equivalence ratio that is frequently lower than the injection equivalence ratio. The stable single-wave mode is primarily achieved under fuel-rich conditions. As the temperature of the air increases, a higher equivalence ratio is required to obtain a stable single-wave mode, and the range of equivalence ratios becomes narrower.