Pre-stress and Free Vibration Optimization of Composite Ocean Current Turbine Blade

Vibration characteristics of an ocean current turbine blade have been analyzed using Finite Element Package Ansys. A vibration analysis determines the natural frequencies and mode shapes of a turbine blade. It can also serve as a starting point for another, more detailed, dynamic analysis, such as a transient dynamic analysis, a harmonic analysis, or a spectrum analysis. The mode shapes and natural frequencies are important parameters in the design of an ocean current turbine blade for dynamic loading conditions. Modal analysis can also be performed on a pre-stressed spinning turbine blade. It has been investigated that the blade would not fail in an ocean current of 2.3~2.5 m/s that can produce power production up to 151 KW. The blade is of Composite structure with carbon fibers and foam core. It is also facilitated with two webs of carbon fibers to add shear rigidity. Eight designs of blade were analyzed involving the differences in shape, material properties and internal structures. Results from the vibration analysis showed that the proposed blade design have adequate frequency difference than the frequency of other components of turbine blade i.e. rotor, assembly to produce proposed power of 151 KW without any resonance failure.