Isolated Consideration of Influence Factors in Open Water Tests of Podded Propulsion Systems

In order to improve the power prediction and propeller design aspects of a podded propulsion system an extensive model test series with four propellers in two scales has been conducted at Potsdam Model Basin (SVA). To isolate the interaction effects between elements of a podded propulsion unit, a range of test setups have been developed including different alternative systems as well as model scale pod units. For all setups, open water tests have been executed. By comparing the results regarding the different setups, interaction coefficients could be determined to describe the influence, isolated parts of the propulsion unit have. The interaction coefficients are calculated analogue to propulsion coefficients in a self-propulsion test. Outcome of this series of model tests is a deeper insight of the effect that especially the shape of the aft fairing can have on the propeller characteristics, causing significant differences. For propeller design purposes of podded drives the knowledge of the interaction between propeller and pod can increase the certainty of the design process significantly. For powering and speed, the prediction of forces acting on the pod housing and the boss cap need to be considered.

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