Computational-fluid-dynamics based advanced ship-airwake database for helicopter flight simulators

Computational fluid dynamics (CFD) is used to create an extensive aerodynamic ship-airwake database for a ship-specific flight simulator to train helicopter pilots for landing and takeoff from various points on a ship. The technology has been embedded into CAE's Merlin simulator and applied to six different ships of the Royal Navy. In achieving this, important scientific and engineering milestones are crossed, including high geometric fidelity through OEM's (Original Equipment Manufacturer) CAD description of the ships, three-dimensional CFD calculations, comparison to experimental data, and, finally, integration, testing, and acceptance into the flight simulator. The database is first built by solving the three-dimensional inviscid (Euler) flow around the complete ship, using Finite Element Navier-Stokes Analysis Package, a proprietary code. And a number of wind speeds and directions, corresponding to realistic approach scenarios, are analyzed. The CFD results are then compared to a set of experiments carried out for airwakes around the Canadian Patrol Frigate and made available only after the calculations were done. The calculations prove to be in excellent agreement with the data throughout its range. For the purpose of integration into the simulator, the CFD solutions are interpolated onto a Cartesian grid, which is then implemented in a look-up table for the Merlin CDS, after being enhanced with turbulence models. The paper then closes with the acceptance procedure the simulator is passed through.