Experimental and numerical investigation of a novel inlet for boundary layer ingesting propulsion systems

Boundary Layer Ingestion (BLI) propulsion systems have the potential to significantly enhance aircraft performance, particularly by improving fuel efficiency and reducing emissions. However, the high total pressure losses and distortions at the outlet of the BLI inlet normally restricts the development of BLI propulsion systems. This paper introduces and investigates a high-performance dual-sided BLI inlet configuration suitable for a large amount of boundary layer ingesting through a combination of computational and experimental methods. The dual-sided BLI inlet has two air entrances located at the top and bottom of the aircraft's rear fuselage, with the two ducts from the upper and lower inlets deflecting towards each other and converging at the same annular outlet. Simulation results indicate that the dual-sided BLI inlet prevents the concentration of low-energy flow observed with single-sided inlets, thereby reducing outlet distortion. Additionally, high-speed wind tunnel tests were conducted to validate the design's feasibility. The test results indicate that the dual-sided BLI inlet demonstrates good performance at the design point (Mfar=0.75, MAIP=0.50, δ/h≈45 %). The total pressure recovery coefficient σfar=0.907 and σin=0.995, the outlet total pressure distortion index DC60=0.24, and the outlet swirl intensity is minor. In conclusion, the novel BLI inlet maintains robust performance under designed conditions, fulfilling the engine's stability requirements.