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Laminar separation and transition have significant effects on aerodynamic characteristics of the wing under the condition of low Reynolds numbers. Using the flow control methods to delay and eliminate laminar separation has great significance. This study uses the method combined with water tunnel test and numerical calculation to research the effects of suction flow control on the flow state and aerodynamic force of the wing at low Reynolds numbers. The effects of suction flow rate and suction location on laminar separation, transition and aerodynamic performance of the wing are further researched. The results of the research show that, the suction can control laminar separation and transition effectively, when the suction holes are in the interior of the separation bubble, and close to the separation point, the suction has the best control effect. When the Reynolds number is Re ¼ 3.0 Â 10 5 , the suction flow control can make the lift-to-drag ratio of the wing increase by 8.62%, and the aerodynamic characteristics of the wing are improved effectively.

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Ground effect is asymmetric when an unmanned aerial vehicle takes off by using the catapult nearest to the edge of the deck from a carrier, because a large part of the wing is out of the deck. Asymmetric ground effect would induce rolling and yawing moments, which are critical factors affecting the safety of takeoff operations. In this research, focus was on asymmetric ground effect, especially on the lateral and directional aerodynamic characteristics. Effects of height, velocity, and wind over deck were studied. Computational fluid dynamics method was used and validated by comparing it with the experimental data presented in early reports. Height is the most important factor that influences lift, rolling moment, and yawing moment. Lateral and directional stabilities are weakened by reducing height. Lateral stability decreased 2.8% and 5.6% as the height was reduced from 1.5 m to 1.2 m and to 1.0 m, respectively. By increasing velocity, lift is increased significantly, while yawing moment is little influenced. Magnitudes of both lift and rolling moment are amplified slightly with the increase of wind over deck. When wind over deck varied from 0 m/s to 15 m/s, lift and rolling moment varied only within 1% and 3.4%, respectively, and thus the effect of wind over deck is secondary.