Investigating ship airwake on a moving ship model

We investigated the turbulent flows on the moving deck of a scaled NATO Generic Destroyer model. The measurements were performed in a large wind-wave interaction facility, allowing the simulation of natural pitching motion. Planar Particle Image Velocimetry was used to obtain the flow structures and the turbulent airwake characteristics on the deck. The results show that the airwake characteristics are strongly affected by both the ship position and its moving direction. The ship-induced velocity directly impacts the flow, inducing strong downwash over the landing deck when the deck is descending around its neutral position. In this study, we divided the ship motion cycle into 8 phases to identify the associated turbulent airwake features, leading to the assessment of the landing safety during different stages of the ship motion. By employing a specified threshold for the standard deviation of the vertical velocity (σ w ), we found that the helicopter will be more likely to encounter extreme turbulent motions with negative pitch angle at typical high hover height on the landing deck. The reverse applies when the helicopter hovers at a higher elevation.