Modelling of Propeller Flows in Harbour
Within the Research Training Group “Ports for Container Ships of Future Generations” a computational method based on the potential theory is developed for the calculation and analysis of propeller induced loads on quay walls and harbor ground.
During the ship maneuvering process the propeller induces a slipstream. This slipstream affects the river bed and quay walls in the harbor. For a better understanding of these complex interactions between ship and port facilities and for the prediction of operational loads induced by propeller flows there is a need in computational simulation tools. For this purpose the in-house simulation code panMare that was developed for the calculation of arbitrary potential flows is extended related to the propeller-quay wall-interaction and cavitation modelling .
For the investigation of propeller induced loads on the port facilities, a three-dimensional panel method is used. The panel method is based on the potential theory, where the flow is assumed to be incompressible, irrotational and inviscid.
Panel methods are used for flow calculations where the viscous effects can be neglected or calculated by other methods. The advantage of such methods is their short calculation time since a three-dimensional problem is reduced to a two-dimensional problem (boundary value problem).
The main goal of this project is to extend the existing in-house simulation code panMare, based on the panel method related to the cavitation modeling and couple this method with other numerical methods.
Cavitation has a significant influence on the pressure distribution in the flow and occurs in many forms. A very common form is the sheet cavitation defined as a closed vapor region attached at the propeller blades. Sheet cavitation operates pressure fluctuations which in turn cause vibrations on the ship hull. In addition, cavitation can lead to noise and erosions, as well as, variations in the developed thrust and torque. Thus it is important to develop a computational method to predict cavitation behaviour of propellers in the design stage.