Computational ship airwake determination to support helicopter-ship dynamic interface assessment

A highly important aspect of safe sea-based helicopter operation is the establishment of ship-helicopter operational limits for current and future helicopter/ship combinations. The capabilities of Computational Fluid Dynamics for the determination of ship airwakes have been investigated, aiming at complementing existing experimental data acquisition techniques consisting of wind tunnel and on-board full-scale measurements. In this paper, computed airwakes based on the Reynolds-averaged Navier-Stokes (RANS) equations as well as on a hybrid RANS-Large Eddy Simulation (LES) approach are compared with experimental data. The resulting airwakes have been converted for usage in a helicopter flight simulator to enable additional feed-back on the reality level of the computational approaches from experienced pilots. It is shown that, from a practical point of view, a useful first impression of the average flow characteristics in the ship airwake can be obtained from steady RANS flow modeling, although the more computationally intensive hybrid RANSLES approach has an inherently better potential for capturing all of the physical content of the fluctuating flow fields.