조류 터빈 블레이드의 하중 감소에 관한 연구

Abstract

Blades of tidal stream turbines are suffered from many different loads during operation in underwater environment thus, acquiring their structural safety is a key issue. Some loads are imposed repeatedly, and some are given impulsively. In this study, we concern an impulsive load due to wave orbital motion and propose a load reduction method with a blade design. The flap of an airplane wing is a famous structure for lift increase, and also it can change load distribution on the wing by its deflection. For this reason, we adopt a passive flap structure for the load reduction and investigate its effectiveness by an analytical method based on the blade element moment theory. Wave induced velocity to the blade is calculated by wave amplitude, submerged depth, blade location etc., and the load is calculated with the modified velocity profile by the induced velocity. For design of the passive flap, flap torsional stiffness is obtained. Comparison between the blade with flap and a fixed blade will show the effect of the flap on the load reduction as well as on regulated power extraction in a high amplitude wave condition