Investigation Of The Similarity Laws Of Slot Flow On Multi-element High-Lift Airfoils

High-lift devices are widely used in the design of aircraft wings. It is not easy to determine the proper configuration of high-lift devices because of the complexity of the flow field around it. Of all devices, multi-element airfoils are the most familiar, of which the parameters of the slots between elements play vital roles. The proper parameters are usually determined by wind-tunnel tests, while the efficiency of wind-tunnel tests are restricted by it scale and thus strongly effected by Re numbers.In the studies described in this thesis, experiments were designed and actualized with a GAW-1 two-element high-lift airfoil in a low-speed 2D airfoil wind tunnel. Lift coefficients (C_l) are gained, as well as the velocity profiles in the slot between the main and flap elements. It is observed that:(1) C_l in the configuration of huge δ f and 0 overlap are high but not very stable as Re changes; (2) as the Re number increases, the boundary layer gets thinner, like is believed before, and detailed velocity profiles are given. (3)the maximum lift coefficients (CLmax) is doubtlessly affected by Re number when Re=0.52×10⁶～2.06×10⁶, in a manner as follows: (4)when Re=0.52×10⁶～1.03×10⁶, the change of C_Lmax is linear at free transition; while at fixed transition, C_Lmax does not change at a certain order; (5)when Re=1.03 ×10⁶～2.06×10⁶ , the changes of C_Lmax at free and fixed transition are linear respectively; (6) Re=1.03×10⁶～2.06×10⁶, when the maximum lift coefficients are fixed, an experiential expression was tried to given in medium range Re numbers, as â–³Gap=-0.00154c â–³Re.The results and methods of this study may be of some value to the experiments and design of multi-element airfoils for UAVs and aero transporters.