Yaw Influence on Unsteady Ship Airwakes and Turbulence Intensity Around the Landing Deck of SFS2 for Shipboard Helicopter Operations*

Unsteady airwake behind a maritime vessel superstructure is modelled using computational fluid dynamics (CFD), as an essential step in optimizing the ship/helipad design and helicopter operational envelopes. This study focuses on simulating the unsteady ship airwakes and turbulence intensity around the SFS2 model under varying wind yaw angles. The objective is to create a sensitivity map of major flow parameters above the flight deck which may be relevant to helicopter operations envelope. This database would subsequently be used to train Machine Learning (ML) algorithms which would predict the unsteady wake properties for different flow conditions. In the current study, wind yaw angles ranging from 0° (headwind) to 180° (tailwind), in 15° increments, are investigated to assess their impact on airwake patterns and turbulence intensity. The results reveal significant variations in airwake structure and turbulence intensity as the wind yaw angle changes. At 0° yaw, a symmetric wake pattern is observed as expected from a mean flow converged over long time-scales. The wake gradually transitions to more asymmetric patterns with increasing yaw angle, especially up to 45°. The major results will be presented in the form of sensitivity maps of velocity and turbulence magnitudes above the helipad, and compared with the existing ship-helo operational envelopes.