AN IMPROVED SINGLE-PARAMETER TIP-TIMING METHOD FOR TURBOMACHINERY BLADE VIBRATION MEASUREMENTS USING OPTICAL LASER PROBES

This paper presents an improved analysis method for the interpretation of the vibration data measured at turbomachinery blade tips using opt ical laser probes. A multi-degree-of-freedom numerical simulator, whic h includes the structural and geometric properties of the bladed-disk assembly, the external forcing terms and the characteristics of the op tical probe, has been developed to assess the reliability of the vario us data processing techniques to identify the natural frequencies and mode shapes of bladed-disk assemblies. It has been demonstrated that t he Zablotsky-Korostelev single parameter technique, which is a de-fact o standard in the aerospace industries, has inherent limitations assoc iated with it. An improved and more rigorous method is presented for d eriving the blade arrival times and a non-linear solution technique is suggested for their numerical determination. Finally, the effect of b lade mistuning on the accuracy of the proposed method is also investig ated. Copyright (C) 1996 Elsevier Science Ltd.