WIND TUNNEL AND ANALYTICAL INVESTIGATION OF OVER-THE-WING PROPULSION/AIR FRAME INTERFERENCES FOR A SHORT-HAUL AIRCRAFT AT MACH NUMBERS FROM 0.6 TO 0.78

摘要

Results of analytical calculations and wind tunnel tests at cruise speeds of a representative four-engine short-haul aircraft employing upper surface blowing (USB) with a supercritical wing are discussed. The wind tunnel tests were conducted in the NASA Lewis 8- by 6-foot tunnel and covered a range of Mach number M from 0.6 to 0.78. The design point for the study was M = 0. 70. The test explored the use of three USB nozzle configurations: (1) a low-angle design with an 11 upper surf ace boattail angle;(2) a streamline contoured nacelle;and (3) a high-angle powered lift design with a 2. 85° upper surface boattail angle. Results are shown for the isolated wing-body and for each of the three nozzle types installed. The experimental results indicate that the low -angle nacelle and the streamline contoured nacelle yielded the same interference drag at the design Mach number. The high-angle powered lift nacelle had higher interference drag primarily because of nacelle boattail low pressures and flow separation. Results of varying the spacing between the nacelles and the use of trailing edge flap deflections, wing upper surface contouring, and a convergent-divergent nozzle to reduce potential adverse jet effects are also discussed. Analytical comparisons with experimental data, made for selected cases, indicate favorable agreement.