Investigations of Ship Airwakes Using Concurrent Computations and Experiments

Abstract

With modern advancements in computational resources, higher fidelity simulations of the ship-rotorcraft dynamic interface using large eddy simulations are now more feasible. Wind tunnel experiments remain one of the best validation tools for computational fluid dynamics simulations, but it is challenging to recreate full-scale ship and atmospheric conditions in such an environment. To serve as a bridge between scaled wind tunnel experiments and full-scale dynamic interface computations, Embry-Riddle Aeronautical University's Boundary-Layer Wind Tunnel was modeled in large eddy simulations to investigate the atmospheric boundary layer's effect on the airwake of a 1:235 scale Simple Frigate Shape 2 model. Cowdrey rods were used in the wind tunnel to develop the turbulence and momentum deficit characteristic of the atmospheric boundary layer. Hot-wire anemometry and Particle Image Velocimetry data were compared to OpenFOAM Large Eddy Simulation data. In uniform inflow conditions, it was found that despite the reduced Reynolds number of the scaled setup, the computational airwake data agreed quite well with larger-scale wind tunnel experiments and full-scale Large Eddy Simulations of the Simple Frigate Shape 2. Comparisons of the experimental and computational simulated atmospheric boundary-layer inflow show good agreement in the time-averaged velocity profile, velocity/turbulence intensity contours along the ship's centerline, and velocity probes on the flight deck of the model.