Flow in the near air wake of a modified frigate

Current naval ships were designed without considerations for the air wake encountered on the flight deck. Naval frigates superstructures design has resulted in a sharp-edges box type that generates a wake dominated by highly turbulent recirculating flows. These flows can affect the safety of the helicopter during the takeoff and landing maneuvers. This paper presents wind tunnel tests performed in order to obtain a more complete insight and understanding of the typical flow on a simple frigate shape. Moreover, a solution to reduce the influence of the wake flow above the flight deck and a risk reduction for on-board helicopter operations is proposed by modifying the usual frigate geometry. Four simple frigate shape hangar roof configurations were investigated by wind tunnel testing. Measurements of the velocity and pressure fields on the flow above the flight deck were performed and results compared in order to evaluate the effectiveness of the modified hangar roof design.