Contribution of different parameters to the thrust deduction of a waterjet propelled hull

Paper in proceeding, 2013

In order to model the waterjet-hull interaction a method, which is based on the potential flow assumption with non-linear free surface boundary conditions, is developed and validated. By means of this method the effect of the sinkage, trim and local flow variation on the resistance increment of a waterjet driven craft has been estimated. Besides, assuming that each of the aforementioned parameters independently influences the resistance change, the resistance increment of the hull is estimated through a linear expansion in a Taylor series, which is a function of the hull sinkage, trim and the flow rate through the waterjet unit. Knowing the magnitude of each single parameter separately helps to understand the physics behind the thrust deduction and may aid in the optimization of the hull/propulsor configuration. Also it sheds some light on the reason for the negative thrust deduction fractions sometimes found on waterjet driven hulls.