Study on geometrical adaptiveness of pre-bend and swept coupled blades.

Sweep rotor blade would reduce blade fatigue load, but induce additional blade root torsional moment. This paper introduces pre-bend/sweep blade to reduce this additional torsional moment. A parameterized mathematical model is developed to define the geometrical configuration of pre-bend/sweep blade with a fully curvilinear axis based on the curves theory of differential geometry. The blade's geometrical configuration is defined by a series of parameters, thus one can change these parameters to get different blades. An aeroelastic model is established based on the coupling of blade element momentum (BEM) theory and geometrically exact beam theory (GEBT). The BEM theory is implemented in an alternative way to enable it to address the spatial curved and twist blade. In order to investigate the aeroelastic behavior of pre-bend/sweep blade, three kinds of blades are built by the parametrized model and then simulated by the aeroelastic model. From the investigation, it is concluded that pre-bend/sweep blade is better than a purely swept blade for the reason that it shows better performance in reducing the blade root torsional moment as well as alleviating vibration. This paper provides a feasible approach to optimize the geometrical configuration of pre-bend/sweep blade for the purpose of adaptiveness.