| The steady aerodynamic loads on a flat plate with uniform porosity in a uniform background flow are determined in closed form by an extension of classical thin airfoil theory. The porous boundary condition on the airfoil surface assumes a linear Darcy law relationship, which furnishes a Fredholm integral equation for the bound vorticity distribution over the airfoil. The solution to this singular integral equation yields a single dimesionless group that determines when porosity effects are important. The pressure distribution, integrated lift, and pitching moment for the uniformily-porous airfoil are shown to be the product of the corresponding impermeable airfoil results and a simple function of the new dimensionless group. |
