Effects of fan speed on the integrated intake-fan-nozzle flow field of a hybrid flying-wing aircraft

Hybrid-powered aircraft that use electric-driven propellers/fans as propulsion devices have advantages such as low pollution, low thermal signals, and low noise, and are an important direction for the future development of the aviation field. To investigate the intake-fan-nozzle flow field of a hybrid-powered flying-wing layout aircraft, this paper establishes a flow field simulation model of the "in-molded intake-electric-driven fan-nozzle" configuration based on the Multiple Reference Frame (MRF) quasi-steady numerical approach, the Shear Stress Transport (SST) k-ω two-equation turbulence model, and the structured grid at the interface between the stationary domain and the rotating domain. The study explores the influence of rotation speed on the intake-fan-nozzle flow field and the underlying flow mechanism by using the fan speed as the research variable. The results show that the addition of the rotating fan can, to some extent, improve the uniformity of air intake in the intake duct, reduce the pressure distortion coefficient at the outlet section of the intake duct, and that the pressure distortion index decreases by 59.7% compared to the case without a fan at 6000 r/min; as the rotational speed increases, the total pressure recovery coefficient changes only slightly, and the pressure distortion index first decreases and then increases. The flow separation of the tip gap flow is gradually intensified with the increase of the tip Mach number, and can disturb the flow in the central area, thereby affecting the flow distribution at the nozzle to a certain extent. The airflow velocity in the nozzle gradually increases along the axial direction as the cross-sectional area decreases; along the radial direction, it first increases and then decreases due to the influence of the flow separation between the tip gap and the central body wall surface.