Subscale Wind Tunnel Experiments on the Aerodynamics of a Rotor Approaching the Landing Deck of a Generic Destroyer

This study presents subscale wind tunnel experiments investigating the transient aerodynamic interactions of a rotor during a continuous relative-wind approach toward the landing deck of the NATO Generic Destroyer. Time-resolved rotor loads and stereoscopic particle image velocimetry measurements were used to characterize the interacting ship-rotor flow field under headwind and quartering wind-over-deck conditions. The measurements captured the evolving influence of ship airwake, ground effect, and superstructure-induced recirculation as the rotor moved from downstream to the final hover position over the deck. The results show that rotor thrust, rolling moment, and pitching moment underwent distinct changes throughout the approach, with the loading trends varying significantly with wind-over-deck angle. Time-frequency analysis further reveals that the unsteady rotor response was concentrated in a limited band of frequencies associated with various coherent flow structures shed from the ship superstructure. Spectral proper orthogonal decomposition was used to identify the dominant airwake features responsible for these fluctuations at specific frequencies, including large-scale structures originating from the radar and hangar region. These findings demonstrate that the dynamic approach resolved both slow- and fast-changing transient aerodynamic effects along the approach path that cannot be captured with static hovering measurements.