Abstract: In order to analyze the influence of unsteady pulsating high pressure in the air-breathing rotating detonation engine combustor on the flow characteristics of inlet and guide the design of the inlet, the spatio-spatial characteristics of the pressure in the outlet section of inlet were considered, the propagation process and flow characteristics of moving shock wave in the inlet were simulated by adopting three-dimensional unsteady numerical simulation method. The configuration characteristics, propagation velocity, pressure and other key parameters of the moving shock wave were analyzed, the flow loss was obtained, and the influence of the angular frequency, peak and time-average values of the pulsating back pressure on the flow characteristics was obtained. The moving shock wave leads to the flow characteristics of low-pressure airflow pressurization and deceleration and high-pressure airflow decompression and acceleration in the inlet, and compared with the steady back pressure condition, the influence boundary of pulsating back pressure is more upstream; the higher the frequency, the longer the circumferential length, the more times the flow passes through the shock wave, however, the average total pressure loss of outlet at different frequencies basically remains unchanged; the time average pressure ratio are kept constant at 12000rad/s and 19.1, respectively, when the pressure peak value ranges from 0.5MPa to 1Mpa, the average total pressure loss of the outlet varies from 43% to 46%; the angular frequency and peak pressure ratio are kept constant at 12000rad/s and 49.5, respectively, when the time-average pressure increases from 0.22MPa to 0.32MPa, the average total pressure loss of the outlet decreases from 52% to 40%, compared with the steady back pressure condition, the total pressure loss is 2%~8% larger. The results show that the unsteady pulsating back pressure leads to the big differences between the flow characteristics of the air-breathing rotating detonation engine inlet and the traditional engine inlet, the flow loss is larger, and the influence boundary of shock wave is closer to the upstream.

Key words: air-breathing mode, unsteady flow, pulsating back pressure, inlet, moving shock wave, flow loss