The Parameter Identification Method of Blade Asynchronous Vibration under Sweep Speed Excitation

Abstract

The non-contact blade tip timing (BTT) measurement, with the advantage of measuring all the disk blades, has obtained widespread applications in industries. The measured data is under-sampled. Generally asynchronous vibrations will appear with the rotating speed sweeping under the excitation of the flow field, which can create a great increase of the blade vibration amplitude that is potentially harmful to the operation reliability of the turbine. In this paper, the investigation on the parameter identification method of blade asynchronous vibration under variable speed excitations was deeply explored. A novel method of parameter identification has been developed, based on the two sensors data interpolation in order to increase the frequency that can be identified. The spectral analysis with all phases Fast Fourier Transform (apFFT) was performed to extract the accuracy amplitude and phase of the blade. The order tracking calculation was carried out based on the minimum angle error. A mathematical model with four blades was developed to simulate the BTT testing data which can produce the simulation of speed sweep asynchronous vibration signal of the four blades. The correctness and accuracy of the algorithm was verified with the parameters identification of blade asynchronous vibration using the simulation model.