A Coupled Navier-Stokes/Full Potential Methodology for the Aerodynamic Study of Unsteady Airfoil Geometries in Unsteady Flow

This Small Business Innovation Research Phase I project proposes a coupled Navier Stokes/Full Potential (NS/FPE) solution methodology for the study of unsteady flow analyses of next-generation helicopter airfoils. The principle behind NS/FPE approach is to divide the physical space being solved into an inner viscous zone near the body surface, and an outer wake zone away from the surface. The Navier-Stokes equations are solved in the inner zone, and the full potential flow equations are solved in the outer zone. The two zones are separated by an interface surface and are tightly coupled through boundary conditions. The Navier-Stokes, inner-zone ensures accurate prediction of viscous separation issues. On the other hand, the outer zone FPE ensures efficient computation of the far-field wake, ensuring fast turn-around times. CFDRC's compressible Navier-Stokes solver will be coupled with a widely used unsteady FPE solver developed by Dr. Banker at Georgia Tech. The developed code will be ble to handle suction/blowing, airfoil deformation for single and multi-element airfoils. The code will be able to naturally handle various complex viscous separation processes such as confluent boundary layers, open separations, and massive separations. In Phase I, the above methodology will be implemented and demonstrated for 2D. Extension to three-dimensional flows and validation/demonstration will be performed in Phase II. The developed methodology will be an invaluable tool in the design and analysis of high performance airfoil shapes. In the era of dramatic shift in the structural construction of the rotor blades with the use of advanced composite materials this tool will satisfy the need for aerodynamic analysis of shape changing airfoils. This methodology will drastically reduce the computational time required for unsteady problems without approximating the full complexity associated with such flow fields.