EFFECTS OF FIXING BOUNDARY-LAYER TRANSITION FOR AN UNSWEPT-WING MODEL AND AN EVALUATION OF POROUS TUNNEL-WALL INTERFERENCE FOR MACH NUMBERS FROM 0.60 TO 1.40

摘要

An investigation has been made in the Ames 2- by 2-foot transonic wind tunnel to determine the aerodynamic effects of fixing boundary-layer transition in a forward location on two unswept-wing models differing only in size and having unswept wings of aspect ratio 3.09 with sharp leading edges. The tests were made at Mach numbers from 0.60 to 1.40 and at Reynolds numbers from 1.5 to 3.45million.nThe effects of fixing transition were very pronounced on the pitching-moment and lift curve slopes at transonic Mach numbers, but were small at Mach numbers above about 1.15. For the fixed-transition condition the variations with Mach number of the pitching-moment and lift curve slopes were much smoother than for the free-transition condition. Within the range of the test Reynolds numbers the effects of fixing transition remained qualitatively the same. The results indicate that for tests at transonic Mach numbers of scale models with unswept wings, it is important to fix transition at locations corresponding to those expected in flight.