Numerical investigation on the ship/multi-helicopter dynamic interface

Abstract

The issue of single helicopter shipboard landing has been widely studied. This paper focuses on the helicopters/ship dynamic interaction for simultaneous landing of two helicopters. A numerical method combining the Detached Eddy Simulation, momentum source model and flight mechanics model via a one-way coupling strategy is developed. With this method, the coupling ship/helicopter flow-field and its effect on unsteady loading and handling behaviors of downwind shipborne helicopter at different conditions are investigated. The results show that in the headwind condition, the super vortex, formed by the upwind rotor wake merging into the deck-edge and superstructure vortex, is a principal factor affecting the downwind helicopter landing operation. Influenced by super vortex, high level of turbulence intensity is evident in the coupling ship airwake, giving rise to a sharp increase in unsteady loading levels and perturbations in control inputs and attitudes, compared with the baseline case (without upwind rotor), and pedal control margin is reduced accordingly. While increasing the translation height can effectively weaken the effect of super vortex, thereby reducing unsteady loading levels and alleviating control margin limits. When wind-over-deck (WOD) angle increases, despite no super vortex formed, the inclined upwind rotor wake interacting with the shear layer in ship airwake results in a higher level of turbulence intensity in the area over the deck. Perturbations in unsteady loading levels, controls and attitudes are more pronounced and complicated than the headwind case, causing great pilot workload.