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Coupled CFD/CSD Analysis of an Active-Twist Rotor in a Wind Tunnel with Experimental Validation

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An unsteady Reynolds averaged Navier-Stokes analysis loosely coupled with a comprehensive rotorcraft code is presented for a second-generation active-twist rotor. High fidelity Navier-Stokes results for three configurations: an isolated rotor, a rotor with fuselage, and a rotor with fuselage mounted in a wind tunnel, are compared to lifting-line theory based comprehensive rotorcraft code calculations and wind tunnel data. Results indicate that CFD/CSD predictions of flapwise bending moments are in good agreement with wind tunnel measurements for configurations with a fuselage, and that modeling the wind tunnel environment does not significantly enhance computed results. Actuated rotor results for the rotor with fuselage configuration are also validated for predictions of vibratory blade loads and fixed-system vibratory loads. Varying levels of agreement with wind tunnel measurements are observed for blade vibratory loads, depending on the load component (flap, lag, or torsion) and the harmonic being examined. Predicted trends in fixed-system vibratory loads are in good agreement with wind tunnel measurements. NOTATION Latin Symbols C p coefficient of pressure M Mach number M β flapwise bending moment, in-lb M θ torsional bending moment, in-lb M ξ chordwise bending moment, in-lb Q second invariant of the velocity gradient tensor r normalized rotor radius U ref X-component of velocity at boundary layer edge (0.995u ∞), ft/sec u X-component of velocity, ft/sec X axial CFD direction y + dimensionless, sublayer-scaled wall coordinate of first node away from surface Y horizontal CFD direction, wall normal direction in boundary layer plots Z vertical CFD direction
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Analysis and Testing of Active Twist Rotor Blades, Master's thesis
  • A R Kreshock
  • Design
Kreshock, A. R., Design, Analysis and Testing of Active Twist Rotor Blades, Master's thesis, Old Dominion University, Norfolk, VA, 2013.