Propeller in Open Water
The prediction of open water propeller data is a standard-task in marine hydrodynamics. Boundary Element Methods (BEM) were primarily designed for the prediction of a propeller's open water performance and panMARE is no exception. The main advantage of potential theory-based panel methods such as panMARE is that they allow for fast and reliable predictions at low computational effort.
Design Stage Propeller Performance Prediction
Using panMARE, open water results can be obtained quickly. This fast and reliable prediction of the propeller's performance makes panMARE particularly suitable for the design process.
A short report including an open water diagram with thrust and torque coefficients and the propeller efficiency can be an output of the program. Since the values are obtainable in text-files, simple comparisons between different propellers and the optimization of the propeller are possible.
Furthermore, a hub geometry can be included in the open water calculation to improve the prediction accuracy of the pressure distribution.
The panel code's hydrodynamic simulation accuracy can be verified by a comparison of the calculated results with values obtained in open water model tests.
Depending on the propeller's geometry, a suitable discretisation can be found, e.g. a discretisation of approximately 28 panels in span-wise (radial) direction and 24 panels in chord-wise direction is a good orientation and can be expected to deliver results of sufficient quality. As can be seen in Figure 3, panMARE (BEM) is able to predict a propeller's open water performance well, since the differences between numerical and experimental results is low.
Extended Hybrid Method
Furthermore, panMARE has been extended by a hybrid method coupling wake alignment of a lifting line method with the boundary element method, as described in detail in Wang (2020). This coupled method maintains all of the BEM's abilities and is significantly faster by using the lifting line method for the wake alignment. Hereby, the accuracy of the obtained open water prediction is only slightly affected by the coupling, as can be seen in Figures 3 and 4.