An actual angle of arrival fitting method for correcting errors induced by speed fluctuation in blade tip timing system.

• Theoretical derivations explored SFPR errors in BTT, confirmed by rigorous experiments and simulations. • Simulation and experimentation verified errors from speed fluctuation on blade frequency spectrum analysis. • An actual angle of arrival fitting method is proposed to correct speed fluctuation errors in BTT. • Simulation and experiment results show the proposed method is more accurate and robust than the conventional method. Blade tip timing (BTT) serves as an innovative non-contact technique for measuring blade tip vibration displacement, offering the capability to conduct online measurements of blade vibrations during operation. Despite its potential, the conventional BTT calculation method encounters significant inaccuracies attributable to speed fluctuation per revolution (SFPR), posing challenges for identifying blade vibration parameters accurately. To address this issue, extensive theoretical derivations were undertaken to comprehensively investigate the factors influencing the error magnitude induced by speed fluctuation. In response to the identified challenges, an innovative approach known as the actual angle of arrival fitting BTT method (AAF) was proposed. This method, grounded in a least square approach, aims to reduce errors caused by SFPR and enhance the precision of blade vibration measurement. The correctness of theoretical derivations and the effectiveness of the AAF BTT method were validated through thorough numerical simulations and experimental verifications, providing valuable insights into improving measurement accuracy. Results from these validations underscored the simplicity, efficiency, and enhanced accuracy afforded by the AAF method in measuring blade tip vibrations. By overcoming the limitations of conventional BTT calculation methods, the AAF approach offers a promising avenue for more accurate and reliable blade tip vibration measurements in various operational contexts. [ABSTRACT FROM AUTHOR]