Abstract

This study has been concerned with numerical predictions of the airwakes resulting from two simplified ship geometries: the internationally agreed Simple Frigate Shape (SFS1) and its successor (SFS2). Extensive steadystate simulations have been carried out for a wide range of wind conditions using Fluent, a commercially available computational fluid dynamics (CFD) code. Preliminary unsteady calculations have also been done. CFD predictions have been validated against wind tunnel data produced by the National Research Council of Canada (NRC) and have shown satisfactory or good agreement. The resulting airwake velocity components have been exported from Fluent, interpolated onto suitable grids and attached to the FLIGHTLAB flight-simulation environment. Using lookup tables, piloted flight trials have been carried out in the Liverpool full-motion simulator. The pilot workload and helicopter control limits resulting from a range of wind-over-deck (WOD) conditions have been used to plot the ship-helicopter operating limits (SHOL) for the SFS2. The workload was compared to the pilot's experiences and the simulated SHOL was contrasted with known SHOL's derived from sea trials, giving encouraging results.