Numerical evaluation of wind direction effects on the turbulence aerodynamics of a ship airwake

Abstract

The airwake characteristics around a ship body are an important consideration for helicopter pilots during shipboard operations, as airwake can lead to the formation of massively turbulent flow over the ship deck. Therefore, this study conducted a delayed detached eddy simulation (DDES) to investigate the impact of the bow part of the ship and the wind direction on the turbulent flow characteristics of the ship deck airwake. Numerical simulations were performed for two different ship models (1:12.5) of the Simple Frigate Shape 1 and 2 (SPF1 and SFS2) to analyze the influence of the bow part on the deck flow-field. Seven different orientations of wind direction angle (HW, RW15, RW30, RW45, RW60, RW75, and RW90) were numerically simulated for SFS1. The time-averaged velocity and pressure fields computed by the DDES approach were validated in comparison to those of the experimental data measured by the PIV data and Kulite pressure sensors, respectively, at various locations over the ship deck. The numerical data revealed that, while the deck flow-field is not influenced by the bow of the ship, the airwake flow is significantly affected by the wind direction angle. Specifically, as the wind direction angle is increased, the turbulent kinetic energy is also increased and the flow-field becomes more asymmetric. Moreover, the spectral analysis and time/space assessment of the flow field showed more pressure fluctuations and a higher level of unsteadiness over the ship deck with a larger wind direction angle, which are important parameters in shipboard operations.