Interference Effects of Very High Bypass Ratio Nacelle Installations on a Low-Wing Transport

A twin-engine, low-wing transport model, with a supercritical wing designed for a cruise Mach number of 0.77 and a lift coefficient of 0.55 was tested in the 16-Foot Transonic Tunnel at NASA Langley Research Center. The purpose of this test was to compare the wing/nacelle interference effects of superfans (very high bypass ratio turbofans, BPR = 18) with the interference effects of advanced turbofans (BPR = 6). Flow-through nacelles were used in this study. Forces and moments on the complete model were measured using a strain gage balance and extensive surface static pressure measurements (383 orifice locations) were made on the model’s wing, nacelles, and pylons. Data were taken at Mach numbers from 0.50 to 0.80 and model angle-of-attack was varied from −4° to +8°. Results of the investigation indicate that superfan nacelles can be installed with approximately the same drag penalty as conventional turbofan nacelles.