Amani_whole_thesis.pdf (7.69 MB)
Numerical and experimental analysis of the wind forces acting on a high-speed catamaran
thesisposted on 2023-05-28, 09:00 authored by Amani, S
The influence of wind on a ship's manoeuvring performance has always been an important issue, particularly in harbour environments, and during the ship's docking or disembarking. Strong wind can force a ship to drift from its intended course of travel which could end in a dramatic accident. The effect of wind loads is even more noticeable on high-speed catamarans which are in general much lighter than conventional ships of a similar size. These types of ships have a relatively shallow draft and a smaller cross-sectional area below the waterline compared with their above waterline area. Therefore, the motion of high-speed wave piercing catamarans due to wind forces can be significant. This research presents 3D steady Reynolds-Averaged Navier-Stocks (RANS) CFD simulations of wind loads on a high speed wave piercing catamaran and validation of the CFD analysis against a new wind tunnel experimental test. It demonstrates, how Computational Fluid Dynamics (CFD) and experimental methods can be used to complement each other in quantifying the magnitude and effects of wind loading on a high-speed catamaran. For the validation, CFD simulations are performed to replicate the experimental test which were performed in the University of Tasmania's wind tunnel. This experiment were carried out on a scale model of a 112m catamaran. The geometrical features of the CFD computational domain were made to be precisely the same as the dimensions of the wind tunnel test section. Preliminary CFD analysis was conducted to determine how the atmospheric boundary layer could be best generated in the experimental test. It was determined the model should be placed on a raised platform allowing the boundary layer profile to be controlled by varying the distance between the model and the leading edge of the platform. This also removed any blockage effects caused by the domain boundaries of the wind tunnel. The experiment was followed by an extensive set of CFD analyses to replicate the experiment. The three-dimensional steady equations were solved with the commercial CFD code Star CCM+. It is shown that the results from the wind tunnel experiment correspond well with the CFD computations. From the analysis results, the required coefficients of wind loading on the 112m high speed wave piercing catamaran were determined which can be used in station keeping analysis of the ship. Agreement between the experiment and CFD simulations shows that CFD is a viable tool for the calculation of wind loading on a full-scale high-speed wave piercing catamaran.
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