Investigation of gurney flap on aerodynamic characteristics of NACA4412 airfoil.

Gurney flap is a flat plate with the height of 1% to 5% chord length attached to the trailing edge of an airfoil. Researches on the effect of Gurney flap show that Gurney flap can significantly improve aerodynamic performance of airfoil. However, most of these researches focus on continuous flow regime, and few on rarefied flow regime. With the development of micro aircraft, the characteristic length scale of airfoil is so small that rarefied effect cannot be neglected. In this paper, Unified Gas Kinetic Scheme (UGKS) is used to investigate the effects of Gurney flap on the aerodynamic characteristics of NACA4412 airfoil with Gurney flap under different Knudsen numbers. The current study confirms that Gurney flap can improve aerodynamic performance from near continuum regime to rarefied flow regime when the angle of attack is smaller than the critical angle of attack. [ABSTRACT FROM AUTHOR]