Lead-Lag Stability Predictions: Why CFD is Needed

Before 2010, the loose and tight coupled computational structural dynamics and computational fluid dynamics (CSD/CFD) analysis was mostly used for the analysis of airloads and structural loads. This paper expands on one of the CSD/CFD methodologies (DYMORE / OVERFLOW) with the aim of validating that high-fidelity aerodynamics, such as provided by the CFD analysis, is the main factor resulting in improved lead-lag stability predictions compared to lifting line solutions. The test data used is the aeroelastic and aeromechanical small-scale rotor stability tests, known as the advanced dynamics rotor. A sensitivity analysis of the airloads performed here indicates that the aerodynamic pitching moment predicted by OVERFLOW has a significant effect on the aeroelastic stability of the system, while the chordwise force does not play a major role.