Full-Phase Leading-Edge Slotted-Slat Design and Optimization for the 30P30N Airfoil in Takeoff, Landing, and Cruise Conditions

Slotted slats can further enhance the lift-enhancing effectiveness of conventional slats, demonstrating superior applicability in scenarios where flaps suffer performance degradation due to water spray impacts during amphibious aircraft takeoff and landing. However, the slotting design compromises the lift-to-drag characteristics in cruise configuration, necessitating advanced strategies to address the inherent conflict between takeoff/landing and cruise aerodynamic requirements. This study focuses on enhancing the aerodynamic characteristics of the 30P30N airfoil by integrating slots into its slat. Straight slots with varying contraction ratios are initially designed, and it is demonstrated that slots with appropriate contraction ratios can significantly improve the lift-to-drag ratio at high angles of attack. The underlying mechanism of this lift enhancement is thoroughly analyzed. To further optimize the slot’s performance, three key parameters are employed to define its geometry, and 20 experimental cases are conducted to determine their optimal ranges. Based on these findings, the Multi-Objective Particle Swarm Optimization (MOPSO) algorithm is applied to refine the slot design. By modifying the slot entrance into rounded corners, an improvement of up to 34.7% in the lift-to-drag ratio is achieved. When the optimized slot is applied to the cruise configuration, it is observed that although drag increases, thereby reducing the lift-to-drag ratio, this effect can be mitigated by curving the straight slot, limiting the decrease to within 0.5%. Finally, the arcuate slot is implemented in the takeoff and landing configuration, resulting in a maximum lift-to-drag ratio improvement of 15.9%. This study underscores the potential of slat slot optimization as an effective strategy for enhancing aerodynamic efficiency in modern aircraft design.