Influence of aerodynamic modeling on the whirl flutter stability of a propeller under axial and non-axial flow conditions

The next generation of propeller-driven aircraft raises new concerns about their stability regarding the whirl flutter phenomenon. This instability has to be evaluated early in the design phase, thereby raising a need for fast and robust prediction methods. The key to analyzing such instability is the modeling of the motion-induced aerodynamic loads on the propeller. This paper proposes to build and compare different aerodynamic modeling methods ranging from low- to mid-fidelity. The comparison of the resulting stability boundaries shows that certain low-fidelity models give results close to mid-fidelity, emphasizing the advantages of these fast low-fidelity methods for the whirl flutter prediction. The interest of mid-fidelity modeling techniques in the study of non-conventional situations is also looked at. In particular, the occurrence of whirl flutter under non-axial flow is studied. The obtained stability boundaries highlight a slight stabilizing influence, demonstrating that the axial flight situation remains a conservative framework for whirl flutter studies.