E., “ A Mathematical Model of Unsteady Aerodynamics and Radial Flow for Application to Helicopter Rotors,” U.S. and Shyy W., “ Shallow and Deep Dynamic Stall for Flapping Low Reynolds Number Airfoils,” Experiments in Fluids, Vol. 46, No. 5, 2009, pp. 883–901. and Bernal L., “ Experiments and Computations on Abstractions of Perching,” AIAA Paper 2010-4943, 2010. V., “ A Computational Study of a Canonical Pitch-Up, Pitch-Down Wing Maneuver,” AIAA Paper 2009-3687, 2009. Crimi P., “ Dynamic Stall,” AGARDograph 172, AGARD, Neuilly-Sur-Seine, France, 1973. and Balleur J., “ The Role of Transition Modeling in CFD Predictions of Static and Dynamic Stall,” Proceedings of the 37th European Rotorcraft Forum, Agustawestland, Sept. 2011. J., “ High-Resolution Computational Fluid Dynamics Predictions for the Static and Dynamic Stall of a Finite-Span OA209 Wing,” Journal of Fluids and Structures, Vol. 78, Nov. 2018, pp. 126–145. and Qin N., “ Investigation of Transition Modelling for a Aerofoil Dynamic Stall,” Proceedings of the 24th International Congress of Aeronautical Sciences, June 2004. and Kompenhaus J., “ Experimental and Numerical Investigations of Dynamic Stall on a Pitching Airfoil,” AIAA Journal, Vol. 34, No. 5, 1996, pp. 982–989. and Price S., “ Simulation of Dynamic Stall for a NACA 0012 Airfoil Using a Vortex Method,” Journal of Fluids and Structures, Vol. 17, No. 6, 2003, pp. 855–874. R., “ Two-Dimensional Unsteady Leading-Edge Separation on a Pitching Airfoil,” AIAA Journal, Vol. 32, No. 4, 1994, pp. 673–681. D., “ Effects of Compressibility, Pitch Rate, and Reynolds Number on Unsteady Incipient Leading-Edge Boundary Layer Separation over a Pitching Airfoil,” Journal of Fluid Mechanics, Vol. 308, Feb. 1996, pp. 195–217. and Shang J., “ Investigation of the Flow Structure Around a Rapidly Pitching Airfoil,” AIAA Journal, Vol. 27, No. 8, 1989, pp. 1044–1051. J., “ The Phenomenon of Dynamic Stall,” NASA TM 81264, 1981. J., “ Unsteady Airfoils,” Annual Review of Fluid Mechanics, Vol. 10, Jan. 1982, pp. 285–311. W., “ Water-Tunnel Experiments on an Oscillating Airfoil at Re = 21,000,” NASA TM 78446, March 1978. J., “ Dynamic Stall Experiments on the NACA0012 Airfoil,” NASA TP 1100, Jan. 1978. W., “ Dynamic Stall Experiments on Oscillating Airfoils,” AIAA Journal, Vol. 14, No. 1, 1976, pp. 57–63. P., “ Unsteady Airfoil Stall, Review and Extension,” Journal of Aircraft, Vol. 8, No. 8, 1971, pp. 609–616. Carta F., “ Unsteady Normal Force on an Airfoil in a Periodically Stalled Inlet Flow,” Journal of Aircraft, Vol. 4, No. 5, 1967, pp. 416–421. Carta F., “ An Analysis of the Stall Flutter Instability of Helicopter Rotor Blades,” Journal of the American Helicopter Society, Vol. 12, No. 4, Oct. 1967, pp. 1–18. Wagner H., “ Über die Entstehung des Dynamischen Auftriebes von Tragflügeln,” Zeitschrift für Angewandte Mathematik und Mechanik, Vol. 5, No. 1, 1925, pp. 17–35. Theodorsen T., “ General Theory of Aerodynamic Instability and the Mechanism of Flutter,” NACA Rept. In addition to formulating a method with limited empirical dependencies, the current research provides valuable insights into the flow physics of unsteady airfoils and their connection to rapidly predictable theoretical parameters. Results from the low-order model are shown to compare excellently with computational and experimental solutions, in terms of both aerodynamic loads and flow-pattern predictions. The resulting model requires only three empirical coefficients for a given airfoil and Reynolds number, which could be obtained from a single moderate-pitch-rate unsteady motion for that airfoil/Reynolds number combination. Large computational datasets are used to understand the flow physics of unsteady airfoils so as to augment an inviscid, unsteady airfoil theory to model the time-dependent viscous effects. In the current work, a physics based low-order method capable of modeling the interactions between the two flow phenomena is developed with the aim of predicting dynamic stall with only a few empirical tuning parameters. Airfoil dynamic stall in incompressible flow is characterized by two interacting viscous flow phenomena: time-varying trailing-edge separation and the shedding of intermittent leading-edge-vortex structures.
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