Large-Eddy Simulation of Low-Reynolds-Number Flow Around Partially Porous Airfoils

Abstract

This paper uses the large-eddy simulation framework in OpenFOAM to investigate the flow characteristics around two-dimensional partially porous airfoils with symmetrical flat geometries, which were used in a previous experiment. The effects of a porous medium near the trailing edge are investigated at a chord Reynolds number of 350,000. Two porous media are modeled to investigate how the porous medium influences the flow around the airfoil and aerodynamic performance: One is a normal porous medium, defined as a homogeneous and isotropic material with identical properties in all directions. The other medium consists of straight holes perpendicular to the airfoil surface, allowing fluid to pass through unidirectionally. It is observed that drag and lift forces vary, depending on the internal structure of the porous medium. The size of the laminar separation bubbles also varies, depending on the parameters of the porous medium, such as the internal structure, the length of the porous section, and the porosity. It is shown that an airfoil with a low-porosity unidirectional porous medium increases the lift-to-drag ratio at high angles of attack as compared with the nonporous airfoil.