Over the past two decades the marine industry has been facing ever more stringent and radical environmental aims. These are not only been defined by the International Maritime Organisation (IMO), but also by individual countries defining limitations to greenhouse gases emitted by vessels. To combat this the industry has turned towards the use of more complex fluid analysis tools, both model scale tests and computational simulations. This analysis has not only focused on hull design, but also on hull roughness, hull propeller rudder interaction and the marine environment. The focus of this PhD research is to develop methodologies that can be utilised within the industry to optimise vessel performance. With this research optimisation aimed towards improving vessel manoeuvring, with focus away from the traditional nondimensional methodologies. To do so, this research aims to lean heavily on the utilisation of Reynolds Averaged Navier Stokes (RANS) method within Computational Fluid Dynamics (CFD). Towing tests have been considered the primary means of evaluating designs, not only for resistance but also for vessel motions. This includes the analysis forces and motions from both waves and manoeuvring tests. These tests however can be time consuming and financially costly. Therefore, the industry has begun to utilise CFD analysis at the early design stage as a low-cost and fast alternative. Not only this, but in recent years CFD has begun to achieve a level of accuracy matching towing tank tests. Due to these factors this research has a focus on the use of such computational means to improve vessel performance, with extensive validation against multiple towing tank tests. The research has a focus on developing and understanding that can be used to quickly evaluate a potential ship design's manoeuvring characteristics. The methodology for simulating a captive harmonic test is presented, which has been validated against towing tank data conducted for the SIMMAN 2014 conference. This methodology is used in conjunction with a fully parametric hull form, developed within this research, to create and evolve equations used for ranking the hull forms manoeuvring performance. These unique equations are used in two optimisations cycles, one on the NPL hull and a further one on a custom hull to improve the vessels performance and efficiency. The optimum NPL hull forms are evaluated through a virtual turning circle manoeuvring simulation in CFD to quantify the improvements made through optimisation. This research developed a novel methodology for ranking manoeuvring characteristics that significantly reduced the overall optimisation time, as well as producing manoeuvring gains over 20% when evaluated in a simulated turning circle manoeuvre. In addition, the research has also presented best practice approaches for developing such a scheme and how to create a parametric setup that enables quick and accurate CFD simulations for complex manoeuvring simulations. This has been extensively validated against benchmark studies of the DTMB hull form from the SIMMAN 14 towing tank data.
|Date of Award||24 Aug 2021|
- University Of Strathclyde
|Sponsors||University of Strathclyde & EPSRC (Engineering and Physical Sciences Research Council)|
|Supervisor||Tahsin Tezdogan (Supervisor) & Osman Turan (Supervisor)|