Elbe Princesse: Evaluation of the Performances of a Paddlewheel Vessel
The client's request was to evaluate the hydrodynamic performance of its passenger ship and to validate the paddlewheel used for propulsion. Bureau Veritas Solutions was asked to perform CFD calm water resistance computations on the passenger ship, as well as computations on the paddlewheel to validate its kinetics, thrust, torque and the vertical force acting on the paddlewheel's floats.
In the first stage of the study, calm water resistance computations were performed with a RANSE VOF free surface CFD solver. The special feature of these computations was that the vessel operates in shallow river water, thus the keel line was only 2.50 m above the river bottom.
The resistance curve was computed for speeds between 13 and 16 km/h, and the increase due to the effect of shallow water was observed between 15 and 16 km/h, where the wave field was much more pronounced.
In the second stage, the paddlewheel's performance was evaluated thanks to an innovative solver, SPH-flow, based on particles described by a Lagrangian method.
The kinematics of the wheel were determined, then applied in the solver to compute the forces and moments of the floats for two rotation rates. The predicted thrust and torque were compared to Volpich's abacus, based on experiments, and the agreement was between -2% and 12%. Each float of the wheel had its own movement, thanks to an eccentric that enabled us to have less water spray. This improved the entrance of the float in the water, and thus enhanced its overall performance.
This study enabled us to determine the passenger ship's hydrodynamic resistance, trim, and sinkage in shallow water. The net increase in resistance due to the bottom effect was observed between 15 and 16 km/h.
The kinematics and performances of the paddlewheel used for the propulsion of the vessel were assessed by Bureau Veritas Solutions thanks to a special solver based on fluid particles. This work enabled the client to validate the performance of the passenger ship and the concept of the paddlewheel with special kinematics.