Automated marine propeller geometry generation of arbitrary configurations and a wake model for far field momentum prediction

This paper first describes procedures and methodologies to automatically produce marine propeller geometry with optional auxiliary bodies such as nozzles, blockages and rudders. This process is designed and implemented for a general boundary element method (the panel method) to deal with both lifting body and non-lifting body flows. The generated geometry is represented by quadrilateral and triangular panels that can be used by other mesh generation codes to produce 3D volumetric mesh for CFD work. The vertices of these generated panels are set so that the normal of the surfaces points inside the body. The order of the panels and their side indices are aligned for numerical procedures such as differentiation of the perturbation doublet potential for surface tangential velocities and Kutta condition at the trailing edge. A DXF file format was also implemented as one of the output files that can be used for propeller manufacturing via CNC and for commercial CFD codes that use geometry data input. Based on the near field wake modeling studies performed by the authors and previous experimental investigations on far wake turbulent jet measurements, a far wake model for a propeller panel method is implemented to enhance the capability of predicting the velocities and momentum impact on the risers under a floating production storage off-loading (FPSO) system during operation. This far wake model consists of contraction wake (within one propeller diameter downstream), transition wake (one to two diameters downstream), and inflation wake (two diameters beyond). Near field velocity prediction of this far wake model is validated using previous LDV measurement. Further experimental studies are scheduled for LDV/PIV measurement up to 20-diameter downstream.Peer reviewed: YesNRC publication: Ye