Measurements of Flow Around an Escort Tug Model with a Yaw Angle

This paper presents the results of experiments to measure flow velocities around the hull of an escort tug model operating at a yaw angle of 45 deg using particle image velocimetry (PIV). The paper describes the setup, calibration, and operation of the PIV system and the analysis of the results, including an estimate of the experimental uncertainty. Flow vectors are given within planes normal to the direction of motion of the tug. One plane was on the upstream side of the hull, and the other plane was on the downstream side of the hull. The downstream measurements were made with and without a low aspect ratio fin, typical of many modern escort tug designs. The results showed that the fin, when fitted, created a large vortex under the hull of the tug. Smaller features of the flow, such as the separation of the flow at the upstream and downstream bilge corners were also defined. The intention of these experiments was to create a data set that can be used to validate computational fluid dynamics (CFD) predictions of flow vectors around an escort tug at a large yaw angle.