Study of the Effects of Axially Defective Blades of Wind Turbine on Vibration Patterns

Abstract

Axial defects in wind turbine blades represent a critical factor influencing both their vibration characteristics and overall operational performance. Among these, the axial cracks are particularly concerning.  They alter the structural dynamics of the blade, compromise stiffness and reduce the ability of the system to withstand fluctuating aerodynamic and mechanical loads. This study presents a systematic vibration analysis of wind turbine blades with three different levels of axial crack defects, specifically of lengths 50 mm, 100 mm, and 350 mm subjected to shaft rotational speeds ranging from 50 rpm to 200 rpm. The experimental investigations are conducted using the Spectra Quest wind turbine simulator. It replicates the conditions of a real wind turbine by incorporating actual wind data from Sohar. The results reveal a strong correlation between defect size, shaft speed and vibration response with regression analysis yielding a high coefficient of determination (R² = 0.98). Further, Taguchi design of experiments is applied to identify the most effective parameter combinations for minimizing vibration risks. The proposed condition monitoring framework demonstrates an effective approach for detecting and mitigating vibration levels in defective blades. Thereby contributing to enhanced reliability, extended service life and reduced maintenance costs in wind turbine systems.