Aerodynamic design of high-lift devices for enhanced low-height takeoff in wing-in-ground effect craft

Wing-in-ground effect (WIG) craft represents a class of high-performance ship, utilizing ground effect to achieve ultra-low-height flight with an exceptional lift-to-drag ratio. However, hydrodynamic constraints during water takeoff impose low takeoff velocity and small angle of attack, severely restricting takeoff weight. To overcome this limitation, WIG craft requires advanced high-lift devices to improve takeoff capability. This study reveals that under ground effect, the high-lift devices experience significant decrease in lift, highlighting the inadequacy of existing design methods under free-stream condition for WIG crafts. To address this challenge, a novel high-lift device design method is proposed, targeting improved low-height takeoff performance in static water conditions. This method introduces an innovative “wing-cutting” parameterization method with comprehensive design space coverage, to enhance the design capability. Numerical validations demonstrate that the designed configuration by this method completely eliminates flow separation above the flaps, achieving a 29.4% increase in takeoff lift compared to the baseline. Furthermore, relative to free-stream-optimized designs, it has an enhanced “high-pressure cushion” under the wing, resulting in an additional 12.6% lift improvement. These results underscore the critical influence of ground effect in aerodynamic design for WIG craft and validate the effectiveness of the proposed method in enhancing low-height takeoff performance.