Pulsation Measurement on Stator Side for Turbocharger Turbine Blade Vibration Monitoring –Effects of Mistuning and Blade Passing Frequencies on Integral Mode Blade Vibration Detections

Authors

Takashi Ando  - Turbo Systems Switzerland Ltd, Switzerland

Abstract

A mechanically robust turbine design with respect to blade vibration is challenging when dealing with nozzle-ring fouling and wear. Especially for engines operating with heavy fuel oil (HFO), the nozzle rings of the turbocharger turbines are prone to severe degradation in terms of contamination with unburned fuel deposits. This contamination may lead to increased excitation of blade resonances in comparison to the nominal design. Due to the statistical character of contamination, long-term monitoring of blade vibration amplitudes would be beneficial. In the harsh environment of HFO operation, however, conventional blade vibration measurement techniques, such as strain gauges or blade tip timing, won’t work reliably for a long period. A previous study [1] provides technical guidelines, on how to extract the relevant information from the pulsation spectra by means of a single pulsation probe installed away from the turbine trailing edge and some sound experimental proofs of integral turbine vibration detections. The theoretical discussions only allude to the effects of unavoidable mistuning as well as interferences due to classical blade passing frequencies on sound radiation patterns, emitted by integral blade modes. In this paper, both effects are thoroughly discussed. Combining the knowledge of theoretical study supported by further experimental results, the application range of this blade vibration detection method will remarkably extend. Reference: [1] T. Ando, Pulsation and Vibration Measurement on Stator Side for Turbocharger Blade Vibration Monitoring, Int. J. Turbomach. Propuls. Power 2020, 5, 11