Abstract
The blade structural fatigue life estimation plays an important role in the manufacturing and operating of wind and tidal turbines. Then identifying the main sources of blade fatigue is of great importance for turbine life predictability. To this end, this paper presents a set of blade-thrust force and blade-root bending moment responses for a scale-model tidal turbine subjected to various unsteady turbulent flow conditions. The influence of the turbulence intensity, the integral length scale and the gaussianity on the blade structural fatigue is then individually investigated. Overall, it is shown that each of these flow characteristics which are intrinsically related, may have a significant impact on blade load fatigue. We then introduce the turbulence parameter taking into account both the integral length scale and the turbulence intensity to better reveal the blade structural fatigue. The non-Gaussian statistics also plays a significant role on blade load. Finally, present results emphasize that it is essential to account for the whole set of the main useful incoming turbulent flow characteristics and also their spatial variations over the rotor sweeping area to conclude on their effects on the turbine structural fatigue.