[125] Blade tip timing monitoring of axial fans with variable blade angle

J Jakl and J Liska
University of West Bohemia in Pilsen, Czech Republic 

This article deals with the blade tip timing (BTT) method of blade vibration measurement used for condition monitoring of variable pitch axial fan blades. The efficiency of axial fans with variable pitch is controlled by adjustment of the blade angle. BTT analysis may lead to incorrect results when only one BTT sensor is used for blade TOA measurement without consideration of the current blade angle and at least two sensors must be used. The method of blade vibration monitoring based on multiple BTT sensors is described in this paper. The suitability of the designed method is verified by a case study.