Propeller-Hull Interaction Effects in waves

Projekt:

Branschprogrammet hållbar sjöfart

Sammanfattning:
This study focuses on understanding the propeller-hull interaction effects not only in calm water but also in presence of waves, ranging from short wavelengths up to large wavelengths (wavelengths of 20% up to 300% of the ship length). The propeller performance and the interaction effects between propeller, hull, and ship appendages are different in presence of waves. Due to the complexity of the problem, propeller-hull
interaction effects in waves have not been fully understood and thus multiple assumptions are being made during a ship design process based on the knowledge that naval architects have gained from more simplified working conditions, e.g. from calm water model measurements. The study is carried out using computational
tools of different fidelity (potential flow solver and viscous flow solver). The results in this report contain a summary of ship motion and added resistance of two different vessels using the aforementioned computational approaches. In this work, as an essential step towards the prediction of interaction effects in waves, bare hull performance prediction in calm water and regular head waves is carried out using two distinct numerical methods. First, a Fully Nonlinear Potential Flow (FNPF) method is used to investigate a ship performance in a broad range of operational conditions. The analysis of the results provided a valuable insight into the ship’s hydrodynamic responses and the correlation between them. Subsequently, a state-of-the-art Computational
Fluid Dynamics (CFD) method is employed using a Reynolds-Averaged Navier-Stokes (RANS) approach.
Besides ship hydrodynamic responses, the results from this method provided detailed information about the flow field around the hull, including its transient nominal wake. In addition, a formal verification and validation (V&V) procedure is applied to understand and control the numerical and modelling errors in the RANS computations. Generally, the results of the employed numerical methods are in good agreement with the
experimental data. The prediction of ship motions and to some extent resistance in the FNPF method is rather accurate, however, due to the higher level of simplifications and approximations in this method, the RANS method is deemed a better candidate for the prediction of ship wake. The computational costs of RANS
methods are 2-3 orders of magnitude higher than that of FNPF. The ship hydrodynamic responses and the flow field analyses from this work can shed more light on the hull wave interaction effects and help the ship/propeller designers to optimize their designs for more realistic conditions than only calm water.

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Författare: Arash Eslamdoost, Mohsen Irannezhad, Martin Kjellberg, Rickard E. Bensow
Utgivare: Lighthouse
Utgivningsdatum: 2022-06-20
Diarienummer: TRV 2019/27023
Antal sidor: 79
Språk: Engelska
Kontaktperson: Charlott Andersson, PLa1us