Measurements of Ship-Airwake-Rotor Coupling Using Controlled Aerodynamic Rotor Scales

Abstract:
An aspect of the ship-helicopter dynamic interface (DI) is the highly unsteady flow environment generated by ship-rotor aerodynamic interactions, which challenges safe launch and recovery operations. To investigate these interactions without the constraints of conventional rotor scaling, a novel airflow-and-blade-frequency (ABF) system was developed, decoupling rotor thrust from blade-passing frequency and enabling independent control of disk loading and periodic excitation. Mean-flow superposition and spectral analyses were used to assess the validity of linear-superposition approaches for DI modeling. While superposition reproduced portions of the interacting mean flow, it failed to capture key features such as superstructure sheltering. Spectral results showed that momentum injection and blade-passing frequency modified the interacting flow through distinct mechanisms. Across all operating conditions, the interacting flow exhibited elevated turbulent kinetic energy at pilot-relevant frequencies over a broader spatial extent than either the isolated airwake or the superposed field, indicating that nonlinear aerodynamic interactions generated flow features that super-positional models did not capture. The persistence of these trends across different ABF operating parameters suggested that correction-based approaches may approximate rotor-feedback effects without requiring fully resolved aerodynamic interactions between the ship and rotor (air)wakes.

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