Flow separation control using the cetacean species nose design

Abstract

Most of the flow separation control devices used in the aircraft wing are effective at high angles of attack, and adversely affect the performance of the wing at low angles of attack. In flight mission, the cruise phase takes major portion than the take-off and landing. Therefore, the flow separation control devices installed on wing may reduce the performance of the aircraft in total flight mission. A bio-inspired passive flow control method is used by introducing leading edge modification. The leading edge modification inspired by the cetacean species (Porpoise) has been analyzed on NACA2412 and NACA66215 airfoils at different subsonic speed using 2D analysis. The effect of the spanwise location and extent of these leading edge modifications is analyzed using a three-dimensional numerical investigation. The porpoise nose design (shorter length and medium depth i.e. depth — 2.25 % of chord, nose length — 0.75 % chord, and nose diameter — 2 % chord) delay the flow separation and improves the aerodynamic efficiency up to the critical Mach number. After critical Mach number, the shock wave formation affects the porpoise nose performance and shows similar flow behavior as base airfoil. A finite wing with a porpoise nose design of full spanwise length showed the better aerodynamic efficiency than base wing model. This rigid design improves aerodynamic performance of a wing without major structural modification.