Abstract: The blade tip-timing technology has improved in recent years and is now frequently utilized in the monitoring and diagnostics of turbomachinery blade vibration. It is necessary to decouple the blade tip-timing measurement results and determine the axial displacement of the blade from them, because the measurement results of the blade tip-timing method are the components of the blade tip displacement in the rotational direction. The change in the posi-tion of the blade tip-timing measurement point caused by the axial displacement of the blade will also introduce the displacement components in the rotational direction. The method of blade axial displacement identification based on blade tip-timing is proposed after an analysis of the link between the change in measurement point position and the measurement result. A sample model of blade tip timing that incorporates blade axial displacement is created in conjunction with the blade profile equation, and the efficiency of the suggested strategy is confirmed by simula-tion. The measured blade tip-timing signals from the adjustable axial displacement aero-engine compressor blade are then used for experimental verification. The axial displacement identification values for the rotor blade are compared to the real values to verify the accuracy of the proposed method. It has significant engineering applica-tion value for the thorough and accurate assessment of blade operation status and rotor-blade axial displacement fault diagnosis.

Key words: blade tip-timing, blade vibration, axial displacement, fault diagnosis, status monitoring