Investigations of the flow resistance of geometries with direction-dependent properties using numerical methods

The flow resistance is an important quantity for the characterization of porous media. It characterizes the pressure gradient over a specimen which is present, when the specimen is subjected to a continuous fluid flow. Recent studies have shown, that the application of porous media within the airfoil of aircraft may reduce the emitted airborne sound of the airfoil trailing edge. Nevertheless, due to its influence on the fuel consumption of the aircraft, maximizing the airfoils lift-to-drag ratio still is of higher concern. A homogeneous porous material, applied to an airfoil, reduces the lift as it connects and thereby declines the pressure difference which generates the resulting lift. Therefore it might be advantageous to apply a direction-dependent material which could positively affect the trailing edge noise but otherwise does not reduce the airfoil lift. In this contribution, numerical calculations of the flow resistance by means of the computational fluid dynamics are presented. In order to basically investigate direction-dependency, simple generic geometries are modeled and their flow resistance is calculated. The modeled problem thereby refers to the standardized measurement of the flow resistance and is validated using experimental data in accordance to the ISO 9053:1991.