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Aerodynamic efficacy of adding yaw-wise rotational degree of freedom to an airplane flap

Kazuhisa Chiba, Tatsuro Komatsu, Takeshi Ito
2020 Aerospace Systems  
This study scrutinized the aerodynamic change of adding a yaw-wise rotational degree of freedom to a single slotted flap of airplane via computational fluid dynamic analyses. Existing slotted flaps have spanwise constant gaps and are disharmonious with the 3D nature of the flow field. A flap geometry and its angle condition are sensitive to aerodynamic performance; small variations in them must be useful in aerodynamic improvement. To add the yaw-wise rotation to a flap is a lower hurdle than
more » ... lower hurdle than to attain other high-lift systems. Therefore, after defining a simple configuration consisting of a fuselage, a wing, and a single slotted flap, we investigated the mesh dependency to consider the diversity in flow phenomena precisely; we examined the effect of the yaw-wise rotation for the flap on improving the whole lift. To place the flap at suitable yaw-wise rotation angles consequently effected raising the lift. We revealed the physical mechanism that accelerating the fluid in the gap between the wing and the flap changes the separation structure on the flap upper surface and grows the lift. Keywords Airplane flap · Aerodynamic performance · Yaw-wise rotational degree of freedom · Computational fluid dynamics Introduction A high-lift device (HLD) is a movable mechanism attached to the wing of an airplane [5] . The demand for gaining airplane speed has optimized airplane geometry to fit the transonic cruise, which is the longest in a flight profile [6] . As a result, as the required lift for subsonic takeoff/landing was deficient, airplanes devised high-lift systems to compensate for this. Modern planes have different geometry design strategies between transonic cruising and subsonic takeoff/landing conditions to accomplish higher speeds. Although to raise the angle of attack enables growing the lift, there is the upper limit due to stall. So, high-lift systems are vital mechanisms not only for prevailing airplanes, but also for next-generation ones, which will speed up in the future. There are three principal types of high-lift systems: the flap mechanism, the boundary-layer control mechanism, and B Kazuhisa Chiba
doi:10.1007/s42401-020-00060-z fatcat:xv37w4zi3nhkrk4debt57vahoe