Thruster-interaction Effects on a DP Semi-submersible and a Drill Ship

AuthorsJ.L. Cozijn and R.Hallmann (MARIN)
Conference/JournalOMAE ASME 32nd International Conference on Ocean, Offshore and Arctic Engineering, Nantes, France
DateJun 1, 2013
Measurement and analysis of the thruster wake flow
Thruster-interaction model tests were carried out in MARIN's Deepwater Towing Tank. Detailed PIV measurements were performed of the wake flow behind the azimuthing thrusters on two different DP vessels, a Semi-submersible and a Drill Ship. The flow velocities were measured in a large number of cross sections at different distances from the thrusters. The PIV measurements provide a detailed image of the flow velocities in the thruster wake, showing the axial velocities, as well as the transverse and vertical velocity components.First, measurements were carried out on a DP Semi-submersible (scale 1:40), which was equipped with 8 azimuthing thrusters. The results of the PIV measurements show the wake flow, interacting with nearby thrusters and the opposite pontoon of the semi-submersible. An example is shown in Figure 1 below. Deflection of the thruster wake, caused by the Coanda effect, was observed. The results for thrusters with a 7 deg downward tilt were compared with the results for thrusters with a horizontal propeller axis. Furthermore, the effect of ambient current was investigated.Second, measurements were carried out on a DP Drill Ship (scale 1:40), which had 6 azimuthing thrusters. The results of these PIV measurements also gave insight in the wake flow behind the
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