Evaluation of a Dynamic Positioning Thruster Wave Using Stereoscopic Particle Image Velocimetry

Thrusters working at low advance coefficients are employed in a wide range of offshore and marine applications on Floating, Production, Storage and Offloading (FPSO) systems; shuttle tankers; tug boats; and mobile offshore units. Therefore, an understanding of the flow around the thrusters is of great practical interest. Despite this interest, there is lack of knowledge in the description of the hydrodynamic characteristics of thrusters wake at bollard pull and low advance coefficient values. This work was aimed at providing detailed data about the hydrodynamic characteristics of a Dynamic Positioning (DP) thruster wake flow at different low advance coefficient values. Wake measurements were made during cavitation tunnel tests carried out on a ducted propeller model at the Italian Ship Model Basin (INSEAN), Rome, Italy. Through these experiments, the DP thruster far wake velocity components at different downstream axial planes, up to 15 diameters downstream, were obtained using a Stereoscopic Particle Image Velocimetry (SPIV) system in the INSEAN cavitation tunnel. These experiments were carried out at two different advance coefficient (J) values [bollard pull (J = 0), and J = 0.4].