Investigation of the structural blade dynamics and aeroelastic behavior of the 7A rotor

Abstract

Deficits in rotor load prediction are often caused by inadequate modeling of structural blade dynamics. The elastic blade behavior needs to be validated as accurately as possible to predict rotor loads precisely. The structural blade dynamics of 1-D and 3-D finite element models in a multibody environment are investigated in terms of frequencies and aeroelastic behavior. Eigenfrequencies of the 1st torsion mode and the 4th flap mode of the reduced 3-D blade model exhibit a stronger coupling than the 1-D analysis prediction. The tightly coupled simulation with the advanced 1-D beam chain modeling approach is used to investigate the aeroelastic behavior of the 7A rotor in high-speed Forward flight. The potential of advanced rotor blade modeling in the multibody software SIMPACK in terms of rotor loads prediction is evaluated. In comparison to experimental data and the loose-coupling environment of ONERA (HOST-elsA), aerodynamical and structural loads are in good agreement. The characteristic 5/rev elastic torsion behavior of the 7A rotor blade has been captured leading to an improvement of the lift force prediction. The coupled SIMPACK-TAU predictions with an advanced 1-D beam model and the HOST-elsA results show a significant improvement over previous computations.