Experimental and Numerical Studies of the Effects of Upper Surface Roughness on Aileron Performance

Wind tunnel studies were carried out to observe the effects of distributed roughness on the upper surface of a NACA 4415 wing-aileron combination. Viscous analysis of the corresponding 2-D airfoil with an aileron was carried out using the 2-D structured multi-block Navier-Stokes (NS) solver NPARC. The two equation k-ω model was used without wall functions as it allows the specification of a surface roughness through the wall boundary condition. Three different configurations, i.e., the Fokker F-28 MK1000 aircraft with aileron deflections, a NASA LS(1)-0417 wing-flap combination and the NACA 4415 wing-aileron combination, were investigated using the 3-D potential/viscous interaction solver PMAL3D. The results of the experiment, 2-D and 3-D numerical calculations were analyzed and compared where suitable. Generally, the numerical studies were consistent with the experiments and showed similar reductions in maximum lift and stall angle of attack. It is also shown from the present work that roughness on an aircraft's lifting surfaces will have significant effects on its aerodynamics and controllability.