Performance of an airfoil with a power-saving, tab-assisted flap system

Wind tunnel;Aerodynamics;Airfoil;Flap;Tab;Performance

Bottalla, Joseph R. ; Bragg ; Michael B.

关键词: Wind tunnel;    Aerodynamics;    Airfoil;    Flap;    Tab;    Performance;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/26028/Bottalla_Joseph.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

This study investigated the feasibility of reducing control surface input power with theuse of a tab-assisted flap. Wind tunnel tests were conducted at the University of Illinois atUrbana-Champaign (UIUC) on a NACA 3415 airfoil model with a flap including a trim tab.Measurements were taken for two configurations: a baseline fixed tab case where tab deflectionwas zero and a tabbed case where multiple flap and tab angle combinations were tested. Hingemoment measurements were taken for both the flap and tab for comparison between the twocases. In addition; lift, drag and moment measurements along with surface pressures wereacquired to aid in the analysis of the concept and provide flow diagnostics. The data werecompared to computational results which compared well with the exception of flap and tabdeflection cases where large regions of unsteady separated flow were present. All data weretaken at a Reynolds number of 1.8 million and Mach number of 0.18.To analyze the power-savings capability of a tab-assisted flap, several studies wereconducted: a generalized tab performance study evaluating hinge moment reduction and a quasidynamicstudy using the static data to calculate work savings for two simulated flap deflections.The generalized tab performance study revealed large hinge moment reductions for each of theflap deflections when using the tab to actuate the flap. These reductions came at the cost ofincreased drag, reduced lift and loss of flap effectiveness. The quasi-dynamic study producedsignificantly large work savings for both simulated flap deflection schedules. Even though thisstudy ignored the effect on lift and drag, as well as the unsteady aerodynamics and controlsurface inertia, it suggests the large power-savings potential of a tab-assisted flap.A flow visualization analysis was performed to further assess the loss of flapeffectiveness observed in the tab performance calculations as well as the non-linear behavior inthe lift, drag and hinge moment data. The results of the analysis showed the complex flowfieldbehavior in cases where the flap and tab deflections were of opposite sign and larger magnitudeand identified the cause of behavior in other cases where data non-linearities existed.