Abstract: The three-dimensional numerical simulation of C₂H₄/Air rotating detonation combustor (RDC) is carried out to study the influence of cavity on the rotating detonation flow field in annular combustor by solving Navier-Stokes equations in the framework of open source computational fluid dynamics software OpenFOAM. The main flow field features of annular and cavity-based annular RDCs are compared under the conditions of total inlet pressure of 0.6 MPa and total temperatures of 300 K, 600 K and 800 K, the influence of cavity on the propagation characteristics of rotating detonation wave is studied, and the proportions of fuel consumed at different heat release rates are quantitatively analyzed. The results show that, for the cavity-based annular RDC, a recirculation zone exists in the cavity, which leads to a slow flow velocity in the upstream of the cavity, but the flow rate significantly accelerates in the contraction section of the cavity. The surface average Mach number at the outlet of RDC is larger than that of the corresponding annular RDC. Due to the lateral expansion of fuel towards the outlet of RDC and the inner wall of cavity, the detonation wave propagating in the cavity-based annular RDC has a higher velocity deficit than that in the annular RDC. Part of the fresh fuel is mixed with the combustion products in the cavity, which increases the temperature of reactant in front of detonation wave. The ratio of fuel consumption under different heat release rates was compared, which shows that the annular RDC consumes more fuel in the form of detonation than the cavity-based annular RDC under the same injection conditions.

Key words: rotatingdetonationflowfield, annularcombustor, cavity, heatreleaserate, propagationcharacteristics