Hangkong bingqi (Jun 2024)
Aerodynamic Characteristics of UAV Taking Off and Landing from Water Surface with Multi-Segment Wing in Ground Effect
Abstract
In order to improve the performance of aerodynamic and take off and landing from water surface, a new biomimetic UAV with multi-segment wing in ground effect is designed based on the hull fuselage, multi-segment wing and T-tai. The pressure nephogram, pressure coefficient and lift-drag characteristics of the UAV in different states are studied in detail with N-S equation and K-Ω-SST turbulence model. The simulation results show that the influence of ground effect decreases with the increase of the UAV height above water. When the ratio of height above water to mean geometric chord (ratio of height to chord H/c) is close to 1, the ground effect is more significant. When the UAV is 0.2 m above water, the lift coefficient and lift-drag ratio increase by 21.91% and 40.37% respectively, and the drag coefficient decreases by 15.22%. For the multi-segment wing layout, the ground effect flight mainly affects the pressure coefficient and pressure nephogram of the lower surface. And the positive pressure amplitude of pressure coefficient in lower surface gradually decreases from inside to outside along the span direction, and the pressure coefficient near the leading and trailing edges along the chord direction is small. With the pressure nephogram, the results show that the impact of ground effect on the growth rate of lift is mainly concentrated in the area below the mid and inner wing. The lift curve slope can be significantly increased by ground effect (increased by 8.89% when H/c is 1). The growth rate of lift coefficient and the decrease rate of drag coefficient gradually increase when the angle of attack increases, and the growth rate of lift-drag ratio (H/c is 1) reaches more than 26% when the angle of attack is greater than 2°. It has been proven that the design has excellent aerodynamic and flight performance with multiple flight tests of verification UAV taking off and landing from water surface and with and without ground effects. The UAV can provide flight platforms for water quality detection, water surface transportation, search and rescue reconnaissance, etc.
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