Rotating stall and surge are common phenomena in compressors, and related research has been carried out since the invention of the gas-turbine engine. Signals of fast response pressure sensors analysed with spectral methods based on Fourier transform are primarily used to characterise compressor stall. This article focuses on the application of blade tip timing (BTT) for this purpose and aims to demonstrate current analysis capabilities, issues and challenges related to practical applications. By using real engine test results, we show that BTT provides more information at the cost of more complex analysis. The signals of four tip timing and three pressure probes installed in the first compressor stage are processed. We observed flow disturbances and blade responses caused by objects located in the inlet at a constant speed and also surge events during snap acceleration. All-blade spectrum and modal tracking are used to identify the presence of non-integral vibration and to determine the nominal frequency and nodal diameter. This data seeds the Least Squares Fitting, which delivers amplitude and phase. A method for sensor fusion is presented. For the selected non-integral responses, tip timing and pressure results are evaluated to show how they can complement each other. The proposed methodology can be used both for compressor development and Blade Health Monitoring.
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