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Item type:Publication, Access status: with files , Multi-fidelity modeling for waterjet propelled high speed small craft(Norwegian University of Science and Technology, Department of Marine Technology, 2024-04-04); ; ; In the present study, multi-fidelity modeling of the Delft catamaran is performed including captive, self-propulsion, and prescribed trim and sinkage simulations. High-fidelity simulations are conducted first to verify the computational setup and validate the computational results. A low-fidelity force and moment propulsion model is implemented based on the high-fidelity simulation results and a hydrostatic correlation, which is applied to self-propulsion simulations. The low-fidelity propulsion model trained based on the high-fidelity computational data shows better simulation results (errors less than 5%D) than using the hydrostatic correlation. The computations are accelerated by a factor up to 8 using the low-fidelity model. Issues for the computational setup including center of gravity, displacement with waterjet system, pump curve, and waterjet flow analysis methods are also addressed. Future work will be focused on the waterjet propelled Generic Prismatic Planing Hull (GPPH) and extending the analysis to maneuvering conditions.Publicationtype: Conference Paper30 105 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Numerical investigation of unsteady pitching foil cavitation(Norwegian University of Science and Technology, Department of Marine Technology, 2024-04-04); ; In the present study, numerical simulations of the unsteady cavitation flows around a pitching foil are performed with a focus on the effects of the pitching motion on the cavity behavior and forces. Sinusoidal pitching motions are imposed to the foil with the reduced frequencies and amplitude in the same range of most practical propeller applications. It has been found that the maximum cavity length decreases with the reduced frequency first and then increases, which is in good agreement with the experimental observations. The simulation results show that the cavity is very unstable at low oscillating frequencies and tends to be stable at high frequencies. The force exhibits the same oscillating frequency and phase as the angle of attack. The amplitude of the lift increases with the frequency, and the mean value of the lift decreases with the frequency first and then increases. The numerical issues and challenges of the simulations of the forced unsteady cavitation flows are addressed. Future work will be focused on scale resolved turbulence and more advanced cavitation models.Publicationtype: Conference Paper36 85