ABSTRACT:

New results of numerical hydrodynamic analysis of the novel offshore cross-flow vertical axis wind turbine with large floating rotor (WEMU design) are presented. The research goals are to investigate a spatial movement of rotary pontoon in incoming regular and irregular waves as well as their influence upon the water ring. Waves are launched by two components of flow velocity and free surface elevation at inlet boundary. Irregular wave is presented according to Pierson - Moskowitz spectrum by sum of first order waves with random phases. Wave loads acting on the pontoon are predicted and hydrodynamic power loss due to waves is calculated.

INTRODUCTION

Offshore wind power engineering is among leaders in the renewable energy sector already for years. And potentially, after solving essential technological and economical problems, its leadership can become absolute. Offshore wind power plants have obvious advantages against located onshore. First, their ecological restrictions are softer; blade speed can be higher, and therefore, an increased efficiency is reachable offshore. Moreover, visual impact of distant offshore wind farms is diminished and territory cost is practically excluded. At the same time, modern offshore turbines inherited their design (propeller installed on tall tower) from onshore and differ only by support structures. So, wellknown drawbacks of propellers could not be excluded. We must indicate here the limited unit power capacity, infrasound emission, and harmful effects on birds and animals. Wind energy cost is still higher than that from conventional power plants. Technological problems quickly grow in large-scale turbines so some research (e.g., Klinger F. et al, 2002) has revealed that an efficient 10MW turbine could not be developed in the one-propeller concept. In this case, wind energy cost will remain relatively high. A technological breakthrough in offshore wind power engineering is still absolutely necessary.

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