Effects of cavity depth on the ethylene-air Continuous Rotating Detonation

Abstract

Continuous Rotating Detonation (CRD) is a promising combustion mode for aerospace propulsion, with high heat release rate and thermodynamic efficiency, but it exhibits realization difficulty for fuels with low chemical activity. To settle this issue, a cavity-based annular combustor scheme has been proposed in our previous study, and its feasibility has been well demonstrated. A series of ethylene-air tests under different cavity configurations have been carried out in this paper, and the effects of cavity depth are revealed. For CRD mode, traditional isobaric combustion also exists at the contact surface between the high temperature burnt products and combustible mixture. Increasing the cavity depth can improve its isobaric combustion holding ability, but excessive isobaric combustion could destroy the foundation of CRD. For fuels with low chemical activity, appropriately improving the isobaric combustion can help the CRD realization. This paper reveals the cavity depth effects on the competitive relationship between isobaric combustion and CRD, and it can be used as a guideline for the CRD combustor design.