Turbulence characteristics of the ship air-wake with two different topside arrangements and inflow conditions

Abstract

We investigate the effect of the Atmospheric Boundary Layer (ABL) and vessel topside arrangement on ship air-wake flow. The investigation is performed by comparing experimental results with two inflow conditions: a simulated ABL and a smooth-wall flat-plate turbulent boundary layer; and two simplified ship models: Simplified Frigate Ship model 2 (SFS2) and NATO-Generic Destroyer (NATO-GD). Particle Image Velocimetry (PIV) and point measurements over the landing deck center-line show that the ABL inflow increases the flow fluctuations but reduces the length of the wake. Furthermore, we observed an enhancement of turbulence energy on the ship landing deck when the ABL is simulated. The data also show that the topside arrangement, especially at the hangar elevation upstream of the landing deck, plays an essential role in the air-wake over the ship center line. There are significant differences in the flow re-circulation regions, turbulence structure and energy content. Based on a turbulence structure and energy spectrum analysis, we highlight regions with a possible increased safety risk for both models. Over the SFS2 center line, regions with an increased safety risk are located directly above the landing deck. Meanwhile, on the NATO-GD center line, these regions are located above the hangar elevation.