Multi-point optimisation of outboard dynamic-inlet waterjet

The Outboard Dynamic Inlet Waterjet is an innovative propulsive system, chatacterized by an high efficiency, a low acustic impact and a remarkable propulsive efficiency, compared to traditional propulsive methods. This type of tecnology offers significant opportunities to improve the sustainability of mobility in particularly sensitive enviroments, such as the Venice lagoon. Through the Impronta-0 project we want to adapt this system to the specific case of the lagoon. This paper focuses on the study concerning the optimization of the engine nacelle shape, with the aim of maximizing the thrust and decreasing the drag in different operating conditions. To do this, an advanced methodological approach based on a Latin Hypercube Sampling has been adopted as an initial step for the selection of a set of individuals for the optimization genetic algorithm. This investigation included the manipulation of the main geometries of the system: inlet, nozzle and external nacelle. These components were modeled through the manipulation of control points, whose interpolation gave rise to the two-dimensional profile of the engine. The systematic variation of these points through an optimization algorithm, together with a CFD analysis for each proposed configuration, allowed to extract the ideal shape for the different operating conditions in which the waterjet is found to operate in the Venice lagoon. The obtained results demonstrate the potential of the outboard waterjet as a sustainable solution for mobility and provide useful indications for further developments of this system in the field of general marine propulsion.