The performance of a marine propeller is degraded by non-ideal operating conditions, including environmental disturbances and vehicle motion. A closed-loop controller can help to overcome these effects and maintain performance. As control law design and implementation requires a model of the system, the propeller must be characterised. To this effect, the performance of a propeller operating behind a towed axisymmetric body was captured via an experimental investigation at the Australian Maritime College (AMC) towing tank. All tests were performed on a generic underwater vehicle geometry with a generic 5-bladed propeller. All experiments were undertaken with the model straight-ahead and deeply submerged. Computational Fluid Dynamics (CFD) and empirical methods were used to estimate the wake deduction factor to calculate the speed of advance. The measured thrust, torque and efficiency curves were compared to open-water propeller curves undertaken on the same propeller geometry at the AMC Cavitation tunnel. Differences in experimental setup compared to the cavitation tunnel were accounted for using the ITTC guidelines regarding Reynolds independence. The carriage velocity and propeller rotational speeds were selected to ensure the same flow regime between both data sets. The results indicate that the open-water propeller curves can provide reasonable estimates of propeller performance in straight-line, deeply submerged condition, provided the wake deduction factor is accurately estimated. This data will be used to demonstrate real-time closed-loop thrust control techniques in future experimental trials. Further work will investigate the impact of model yaw and aft-control surface deflections on propeller performance.
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