Macroscopic Time-Resolved Study on Reactive Flow Structure in a Gas-Solid Multiphase Cylindrical Rotating Detonation Combustor

The rotating detonation combustor (RDC) is subject to high heat loads due to high temperature gases and complex flow structures caused by detonation wave. For cooling wall of the combustor, the ablator such as a C/C composite is inserted and observed highly erosion in the detonation propagation region. Focusing on this erosion effect, our research group has proposed an RDC system in which the ablator is replaced by solid fuel. And this RDC system is referred to as a gas-solid multiphase rotating detonation combustor (GSM-RDC). GSM-RDC is characterized by an increase in thrust by combustion of vaporized gas; however, the influence of the time-varying inner diameter on the detonation structure and overall combustion characteristics has not yet been clarified. To address this gap, the present study conducts long-duration (< 3 s) combustion tests and performs time-resolved measurements of axial pressure distributions under wall regression. The objective is to elucidate the temporal behavior of the combustion mode, detonation propagation structure in relation to the dynamically changing chamber geometry. Combustion tests are conducted in a cylindrical GSM-RDC, using oxygen and ethylene as gaseous propellants and polyethylene as the solid fuel. Comparison with the SUS-wall combustor showed that the combustion pressure increased markedly behind the detonation propagation region. It is suggested that combustion of the vaporized gas influenced the pressure increase. As the inner diameter of polyethylene increased, the detonation propagation frequency decreased slightly, and the pressure distribution gradually became flatter.