| Summary: | The interaction between a bluff body and the impinging fluid flow, can involve detached boundary layers, massive flow separations, free shear layers, development of recirculation zones and formation of a highly disturbed and complex region downstream of the bluff body, which can be categorized as wake. The present research aims to experimentally investigate such fluid-structure interaction and provide insight into the wake structure of two bluff bodies. To this end, the airwake over the helicopter platform of a Canadian Coast Guard (CCG) polar icebreaker was studied using high-speed particle image velocimetry (PIV). The experiments were conducted on a scaled model of the polar icebreaker situated on a costume-built and computer-controlled turntable, which provided the ability to accurately change the incidence angle of the impinging flow with a given rate of change for incidence angle. Quantitative flow field data were obtained in several vertical and horizontal planes. The obtained velocity field was then used to calculate the time-averaged flow structure and turbulence metrics over the helicopter platform of the vessel. The present work compared the effects of two types of inflow conditions: (i) a uniform flow and (ii) a simulated atmospheric boundary layer (ABL) on the flow structure over the helicopter platform of the ship. Moreover, for the bluff scaled model, the effects of the Reynolds number on the wake structure and the flow patterns were investigated. The incidence angle (α) between the oncoming flow and the orientation of the ship varied between 0° to 330° with the increment of 30°. It was observed that higher maximum values of the turbulence intensity were associated with the simulated ABL. Moreover, it was found that for both inflow conditions, the incidence angle of 300o corresponded to the highest turbulence levels over the helicopter platform. Building on the results obtained for a stationary vessel in the simulated ABL, this work aimed to quantify the effects of the unsteady change in the ...
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