Effects of Cavity Location on Ethylene–Air Continuous Rotating Detonation in a Cavity-based Annular Combustor

ABSTRACT

To settle the realization difficulty of continuous rotating detonation (CRD) fueled by hydrocarbon, a cavity-based annular combustor scheme was proposed in our previous study, and its feasibility was well demonstrated. This paper mainly focuses on effects of the cavity location on CRD. The results show that the CRD operating range reduces, as the cavity moves downstream. When cavity is arranged in the detonation zone, the cavity-stabilized flame is coordinated with the reaction zone of detonation. The cavity can intensify the CRD initiation, and CRD waves propagate as co-rotating two-wave mode with higher outlet pressure, higher frequency, and higher stability. When cavity is downstream arranged out the detonation zone, it has little impact on improving the CRD initiation. CRD waves propagate as counter-rotating two-wave mode with lower outlet pressure, lower frequency, and poor stability. In these cases, the majority of reaction zone of detonation concentrates on the upstream annular part, and the cavity-stabilized flame is separated from the reaction zone of detonation, acting as afterburning. A new quantitative approach, the axial distribution of chemiluminescence intensity, has been proposed in this paper, and the separation and move processes of cavity-stabilized flame are verified quantitatively based on it.

KEYWORDS:

• Continuous rotating detonation
• cavity location
• ethylene
• cavity-stabilized flame
• optical observation

Additional information

Funding

This work is supported by the National Natural Science Foundation of China: [Grant Numbers 51776220 and 91541103].