Blade Tip-timing Measurement Mathematical Modeling and Simulation Without OPR Under the Condition of Rotating Speed Fluctuation

The tip-timing measurement without the OPR (once-per-revolution) signals is a non-contact blade vibration measurement method. It measures blade vibration by monitoring the time of arrival (ToA) of the blade. It affects the accuracy of the ToA that including blade assembly mistuning, coupled vibration, rotating speed fluctuation, measurement system noise, etc. However, it is difficult to complete the study of the influencing factors of this method due to the lack of a standard tip-timing data source. This paper derived the relationship between rotating speed fluctuation, vibration displacement, and the ToA. The model simulating the tip-timing measurement without OPR was established. This model realized the simulation of tip-timing measurement without OPR under the condition of rotating speed fluctuation. It can provide the standard tip-timing data for performance verification of the tip-timing measurement method without OPR. Besides, the measurement accuracy of the linear fitting method without OPR was verified, and the factors influencing the fitting accuracy were analyzed.