11th European Conference on Turbomachinery Fluid dynamics & Thermodynamics
A Blade Tip Timing (BTT) system enables the measurement of turbomachinery blade vibrations by means of contactless sensors mounted in the casing. In addition, the so-called Blade Tip Clearance (BTC) measurement system ensures the monitoring of the existing running gaps between the blade tip and the casing. This paper focuses on the results achieved so far using a novel magnetoresistive sensor for simultaneous BTT and BTC measurements. Several prototypes of the probe have been realized and tested. Measurements of clearance are possible with an uncertainty of U = ± 22 µm (20:1) within a gap range [1 ÷ 1.5] mm, in line with the commonly used probes. In terms of measurement of vibration, a dedicated calibration bench for any type of BTT and BTC probe was realized. Experimental investigations are presented. The magnetoresistive sensor has low manufacturing costs and the metrological characteristics fulfill the requirements of industrial instrumentation standards.