Abstract
Blade tip timing is a technique for the measurement of vibrations in rotating bladed assemblies. In Part I of this work a class of methods for the analysis of blade tip timing data from bladed assemblies undergoing two simultaneous synchronous resonances was developed. The approaches were demonstrated using data from a mathematical simulation of tip timing data. In Part II the methods are validated on an experimental test rig. First, the construction and characteristics of the rig will be discussed. Then, the performance of the analysis techniques when applied to data from the rig will be compared and analysed. It is shown that accurate frequency estimates are obtained by all the methods for both single and double resonances. Furthermore, the recovered frequencies are used to calculate the amplitudes of the blade tip responses. The presence of mistuning in the bladed assembly does not affect the performance of the new techniques.
Highlights
The general characteristics of blade tip timing (BTT) as a method for measuring vibrations in rotating bladed assemblies have already been discussed in Part I of this work
Strain gauges connected to a 24channel slip ring and up to ten fibre-optic BTT probes were used for data acquisition
Single resonance case: 2EO excitation. This case is intended to show that the two-degree-of-freedom methods developed in Part I are general enough to work for cases were there is only a single synchronous resonance in the BTT data
Summary
The general characteristics of blade tip timing (BTT) as a method for measuring vibrations in rotating bladed assemblies have already been discussed in Part I of this work. It was shown that, significant work has been carried out in developing analysis methods for BTT data, little research has been published concerning the development of techniques for the analysis of data from assemblies undergoing two simultaneous synchronous (or one synchronous and one asynchronous) resonances. The methods are based on an autoregressive curve-fit of the BTT data, designed to identify two or more modes, either damped or undamped. The new methods were validated using a mathematical BTT data simulator. In Part II of this work the new methods will be applied to BTT data from an experimental test rig. The rig was designed to produce high quality BTT data from synchronous resonances. The results from the application of the methods to experimental data will be presented and analysed
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