Inclined Screens for Control of Ship Air Wakes

*† The results of a wind tunnel investigation of novel flow control devices applied to a generic frigate flight-deck are presented. A range of inclined porous screens were mounted around the hangar door area, with the intention of reducing both turbulence levels and downwash velocities in the ship airwake, which should in turn improve pilot workload and helicopter performance. Overall, a dense screen, mounted on the sides and roof of the hangar and inclined rearwards was found to give the best performance. Addition of a horizontal screen along the flight-deck edges gave a further improvement in turbulence. Device effectiveness was strongly dependent on the region of interest for flight operations, with the greatest improvements obtained lower down in the lee of the hangar. The effect of crosswind was to radically change the flowfield over the flight-deck, giving rise to a highly turbulent vortex flow apparently separating from the deck surface.