Shifting Straight-Line Fitting Method to Calculate Blade Vibration Based on Blade Tip Timing

Blade tip timing (BTT) technology is a research hotspot and can directly estimate the blade vibration, which is of great significance to blade fault diagnosis. However, the traditional once per revolution (OPR) method has greatly limited the application of this technology due to the installation problem of the sensor and low measurement accuracy. In order to overcome the disadvantages of the OPR method, this article proposes a shifting straight-line fitting (SSLF) method to accurately calculate the blade vibration. The principle of the SSLF method is to obtain the expected arrival time of the optimal fitting point by shifting the straight-line fitting (SLF), and the vibration of the blade can be obtained according to the time. In this article, first, a brief introduction of BTT technology and the OPR method is given. Then, theoretical analysis and experimental investigations are used to verify the effectiveness of the SSLF method. In the end, the SSLF method is applied to the large centrifugal compressor, which can be concluded that the SSLF method can be used for blade monitoring of the compressor based on the investigation of experiments.