Accurate Numerical Flow Simulation of Hovering Rotors using different Transition Prediction Methods
C.C. Heister, J. Raddatz and A. Klein, Presented at: 36th European Rotorcraft Forum, September 7-9, 2010, Paris, France
In order to numerically determine the laminar-turbulent transition on hovering rotors, the applicability of three different prediction methods originating from fixed wing applications has been investigated. This includes the AHD method, used with approximated boundary layer data, and the Drela e^N envelope method, using integral boundary layer parameters. Both methods are implemented in the structured flow solver FLOWer. Furthermore, a boundary layer / e^N stability code coupled to the hybrid flow solver TAU was taken into account. One two-dimensional test case (Somers airfoil) and two three-dimensional hovering rotor test cases (ONERA 7A rotor and DLR Bo 105 flight test) serve to test and validate predicted transition and its influence on rotor performance.