An experimental investigation of resonant response of mistuned fan and compressor rotors utilizing NSMS
Abstract
This research was directed at investigating the resonant response of mistuned fan and compressor rotors which can lead to high cycle fatigue failure of turbomachinery blading. These benchmark data will serve as the fundamental foundation for the validation and development of accurate advanced design systems for the analysis of forced response and HCF, including structural mistuning, of axial flow rotors which are typical of those utilized in both front and aft stages of modern high pressure compressors, i.e. rotors designed for transonic and subsonic relative flow fields. This objective was pursued by means of experiments to measure the resonant tip deflection of the blades utilizing NSMS. The resonant response of the blading was measured on the second of three stages of an axial compressor and on a single stage transonic compressor rotor. Each rotor's natural frequencies and mode shapes are determined using FEA with the corresponding Campbell diagrams generated for each rotor. The resonant modal deformation from FEA is scaled by the measured deflection and used to solve for the resonant stress. The performance of the 3-stage axial compressor is measured in order to locate the resonances on the performance map. The second stage rotor on the 3-stage compressor was found to have less than 2% mistuning for the first bend mode and less than 0.6% for the first torsion mode. The mean predicted stress at low and high loading is 21.2 and 12.4 ksi for the first bending mode and 23.6 and 9.9 ksi for the first torsion mode. The transonic rotor first bending mode frequency mistuning is less than 1% with the predicted mean stress of 1.0 ksi. The first torsion mode frequency mistuning is less than 3.5% with the predicted mean stress of 15.5 ksi. The transonic rotor frequency mistuning for the second bend mode was less than 5% with the mean predicted stress being 3.6, 5.3, and 6.3 ksi for the low, nominal, and high loading conditions.
Degree
Ph.D.
Advisors
Fleeter, Purdue University.
Subject Area
Mechanical engineering
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