Thruster-Interaction Effects on a DP Shuttle Tanker - Wake Flow Measurements of the Main Propeller and Bow Tunnel Thrusters

This paper discusses thruster interaction effects for a DP shuttle tanker, equipped with two main propellers and rudders, as well as two bow tunnel thrusters. Thruster-interaction model tests were carried out in MARIN’s Deepwater Towing Tank. Detailed PIV measurements were taken of the wake flow behind the main propellers and rudders. Furthermore, PIV measurements were taken of the wake flow of one of the two bow tunnel thrusters. The flow velocities were measured in a large number of cross sections at different down-stream positions. The PIV measurements provide a detailed image of the velocities in the thruster wake, showing axial velocities, as well as transverse and vertical velocity components.
The results of the first set of measurements showed in detail the wake flow behind the main propeller of the DP shuttle tanker. The wake flow pattern was determined at rudder angles of 0 deg and 10 deg. Since the research is related to DP performance, bollard pull conditions (zero forward speed) were considered in the model tests.
The results of the second set of measurements showed in detail the wake flow of one of the bow tunnel thrusters. The wake flow pattern was investigated in zero speed conditions, as well as for the vessel at forward speed. The observed flow patterns helped to explain the reduced bow tunnel performance at forward speed.
The results of the present research are used to further improve the understanding of the physics of thruster interaction effects. Furthermore, the results will serve as validation material for CFD calculations that are currently being performed.