Flow Structures of Ship Airwakes with Quartering Winds

Abstract

The unsteady, three-dimensional, turbulent airwake over the Simple Frigate Ship No. 2 (SFS2) with quartering wind flow directions was studied in a low-speed wind tunnel. Time-resolved stereoscopic and planar particle image velocimetry (PIV) measurements were made and supported by surface oil flow visualization. Measurements included various configurations with the bow of the ship model at two different quartering wind conditions of 10 and 20 degrees, as well as cases with and without the effects of a simulated atmospheric boundary layer (sABL). A comparative analysis of the flow structures between the quartering wind cases and the pure headwind measurements showed significant differences in the development of the airwake. For both quartering wind cases, the funnel wake had a trailing vortex on the windward side and was associated with significant local flow velocities. In addition, the flight deck recirculation region decreased in size and became asymmetric. Overall, significantly different flight deck flow structures were found, indicating that the effects of the yaw angle were important.