Aeroelastic Flutter Analysis for Advanced Propeller Design

Within the TorPropel project, aeroelastic flutter is addressed as a key challenge in the design and operation of advanced aircraft propellers. Flutter is a dynamic instability arising from the interaction of unsteady aerodynamic loads, structural elasticity, and inertial forces, representing a critical limitation for lightweight, high-performance propeller systems. Accurate prediction of flutter behavior is essential to ensure structural integrity, operational safety, and reliable performance across the flight envelope.

Modern propeller concepts increasingly rely on lightweight composite structures to achieve high aerodynamic efficiency, noise reduction, and improved fuel economy. However, their increased flexibility also raises susceptibility to aeroelastic effects, particularly bending–torsion coupling, which can lead to flutter at lower operating speeds if not properly addressed during design. Robust flutter analysis is therefore essential for the certification of next-generation propeller concepts, including toroidal propellers.

Within TorPropel, aeroelastic stability is investigated by Technical University of Munich using a decoupled fluid–structure interaction (FSI) approach for subsonic conditions. Structural modal analyses are first conducted to determine natural frequencies and mode shapes under rotational prestress. These results are then coupled with unsteady aerodynamic simulations to assess energy exchange between the blade and the surrounding flow. The energy method is applied to compute aerodynamic damping and identify flutter onset.

The influence of blade geometry, mass distribution, stiffness, and rotational speed on flutter stability is systematically evaluated. Numerical predictions are further validated through post-processing of unsteady pressure fields, blade loading histories, and frequency-domain analyses to ensure consistency between aerodynamic and structural responses.

Overall, the TorPropel flutter investigations provide important guidelines for the safe design of advanced propeller systems. By integrating high-fidelity aeroelastic analysis early in the design process, the project contributes to improved flutter margins and reduced risk of dynamic instability in novel propeller architectures.