Papers Published

1. Tang, D.M. and Dowell, E.H., Experimental and theoretical study for nonlinear aeroelastic behavior of a flexible rotor blade, AIAA Journal, vol. 31 no. 6 (1993), pp. 1133 - 1142 .
   (last updated on 2007/04/10)

   Abstract:
   The purpose of this paper is to study the flutter instability and forced response of a nonrotating flexible rotor blade model with a geometrical structural nonlinearity and a freeplay structural nonlinearity. The ONERA stall aerodynamic model is used. External excitations are provided by base harmonic excitations in the pitch angle and the chordwise direction, respectively. Two cases are considered in this paper. Case A is for a nonlinear blade structure with an unstalled unsteady aerodynamic model. Case B is for the nonlinear blade structure with a large effective mean angle of attack. The effects of the structural and aerodynamic nonlinearities and initial disturbance on instability and forced response behavior are discussed. A wind-tunnel test has also been carried out in the Duke University low-speed wind tunnel. The wind-tunnel tests show generally good agreement between theory and experiment for both static and dynamic behavior. Although the mathematical and experimental model of the nonrotating blade is different from the operational rotating hingeless rotor blade, the results from the experimental-theoretical correlation study provide fundamental understanding of the nonlinear aeroelastic behavior for a flexural-flexural-torsional hingeless rotor blade.

   Keywords:
   Helicopter rotors;Flutter (aerodynamics);Stability;Dynamic response;Mathematical models;Wind tunnels;Nonlinear equations;Structural analysis;Aerodynamics;Fluid structure interaction;Flexible structures;