Abstract
As the use of wind power continues to increase globally, the need for improved structural health monitoring systems for wind turbine blades increases as well. Acoustics-based methods are deemed promising in this endeavor, as they are non-contact, nondestructive and enabling distributed sensing. To systematically design an acoustics-based blade health monitoring system, a representative computational study using a NACA 0012 airfoil was conducted to examine the impact of damage location, damage size, acoustic source location, and microphone placement on the detection rate. Structural-acoustic coupled simulations were performed using a commercially available finite element based tool. Results indicated that sound pressure levels (SPL) did not increase significantly when the damage was not near the source location, indicating that using a change in SPL to identify damage may not be the best method. However, spatial variability of the change in SPL in the blade’s internal cavity was found to be a strong indicator of damage, resulting in a detection rate of 81–92% depending on the damage size. Based on the computationally obtained results, the recommendation is for further investigation into the spatial variation of sound inside the blade cavity using 2–3 microphones per cavity to identify damage, when feasible, in addition to testing the effectiveness of a one microphone per cavity design with different blade geometries. The optimal positions of these microphones and the reliability of this method will continue to be investigated in future work.
