Robust Prediction of High Lift Using Surface Vorticity

FlightStream has been developed a fast, accurate, aerodynamic prediction code based on vorticity computations on the surface of an aircraft. The code, though still a surface paneling algorithm, has proven to be significantly more robust and computationally efficient. FlightStream uses CAD or an unstructured surface mesh and is adaptable to subpanels varying in vertex valence from triangles to surface polygons. The focus of the recently completed Phase-I effort preceding this proposal has been to develop the viscous formulation of surface-vorticity to allow the prediction of non-linear aerodynamics and the onset of flow separation through a new approach called the Fluid Strain-based Separation model. This theoretical development and demonstration has laid the foundation for an effective, high-fidelity, physics-based solution for flow separation. In this Phase-II proposal, the focus is to expand the scope of application of these non-linear aerodynamics and flow separation models through robust algorithmic implementation to the FlightStream code base. A part of this focus will also be to validate the conclusions obtained from the strain-based separation model about the nature of fluid flow and to develop fundamental relationships between the proposed Maximum Fluid Strain property and the primary fluid properties with regard to flow separation. Several major performance and fidelity enhancements are also proposed for this effort that are expected to place FlightStream in a very unique position in the aerospace industry. These include the application of the Fast Multipole Method for improving the solver speed and reducing its memory footprint; a higher-order vorticity sheet solver to improve the fidelity of the solutions and improve solver stability in non-linear flow environments and other mutually supporting enhancements. Research in Flight hopes to use this current effort to develop the very first commercially viable viscous, surface-vorticity, flow solver.