An Overview of Analysis and Design of Offshore Wind Turbines

Offshore wind provides an important source of renewable energy and new opportunities for marine technology. Various fixed and floating concepts have been proposed for offshore wind application. Offshore wind turbines (OWTs) with a monopile support structure fixed to the sea bed in shallow water, have already been industrialized, while fixed turbines in deeper water are emerging. Floating wind turbines are still at an early stage of development. The works presented in this chapter deal with selected recent developments of wind turbine concepts, design criteria and methods for integrated dynamic analysis. Besides design, topics such as inspection, monitoring, maintenance and repair during operation are also briefly addressed

The Specialist Committee on Wake Fields Final Reports and Recommendations to the 25th ITTC

The recommended actions of 25th ITTC Specialist Committee on Wake-Fields, as stated above are focused on two main areas, the review of the numerical prediction and experimental measurement (methods) of wakefields and the review and development of ITTC procedures

Numerical assessment of propeller-hull interaction and propeller hub effects for a twin screw vessel

A numerical study that addresses twin screw propulsion was conducted and results using the RANS solvers ‘FreSCo+’ and ‘Fluent’ were shared. In order to avoid potential problems on property rights we combined the DTMB (David Taylor Model Basin) model No. 5415 and the SVA (Potsdam Model Basin) propeller No. CPP 1304. The computational self-propulsion point was identified via a numerical implementation of the so-called ‘British Method’. In this particular case, linked to the hub dimensions of the chosen propeller, the detailed modelling of the propeller hub and the true resolution of its connection to the hull was rather important. The same view holds for the propeller open water test setup. For the latter case we learned that the comparison with uncorrected experimental thrust data could represent a better way to confirm the numerical results

Application of Vortex Flow Model in Propeller-Stator System Design and Analysis

The paper covers basics of the vortex model used for propeller-stator systems. The outline of the design algorithm is given and the results of its application are shown. The designed propeller-stator system was the subject of model tests run at the CTO model basin and cavitation tunnel. Stator’s influence on the delivered power required by the propeller and its revolution rate has been examined by conducting self-propulsion tests with and without stator. The tests performed in the cavitation tunnel revealed only weak tip vortex cavitation on the propeller. No cavitation was observed on the stator at the design point. A wide range of the performed tests allowed the authors to identify details of the developed theory which will require further improvement

Numerical Analysis of the Unsteady Propeller Performance in the Ship Wake Modified By Different Wake Improvement Devices

The paper presents the summary of results of the numerical analysis of the unsteady propeller performance in the non-uniform ship wake modified by the different wake improvement devices. This analysis is performed using the lifting surface program DUNCAN for unsteady propeller analysis. Te object of the analysis is a 7000 ton chemical tanker, for which four different types of the wake improvement devices have been designed: two vortex generators, a pre-swirl stator, and a boundary layer alignment device. These produced five different cases of the ship wake structure: the original hull and hull equipped alternatively with four wake improvement devices. Two different propellers were analyzed in these five wake fields, one being the original reference propeller P0 and the other - a specially designed, optimized propeller P3. Te analyzed parameters were the pictures of unsteady cavitation on propeller blades, harmonics of pressure pulses generated by the cavitating propellers in the selected points and the fluctuating bearing forces on the propeller shaft. Some of the calculated cavitation phenomena were confronted with the experimental. Te objective of the calculations was to demonstrate the differences in the calculated unsteady propeller performance resulting from the application of different wake improvement devices. Te analysis and discussion of the results, together with the appropriate conclusions, are included in the paper