Analysis of dynamics of bladed discs with monocrystalline anisotropic blades

Boruah, Dibakor (2016) Analysis of dynamics of bladed discs with monocrystalline anisotropic blades. Masters thesis , University of Sussex.

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Abstract

The present study aims to quantify the effect of material anisotropic orientations on the dynamics of a gas turbine bladed disc with monocrystalline anisotropic blades (nickel-based superalloy DZ125). In consequence, a single blade finite element model has been created to analyse the effect of material anisotropy on the modal properties of a single blade of a gas turbine. Correspondingly, a finite element sector model with cyclic symmetry has been generated to analyse the influence of anisotropic material orientations on the natural frequency and mode shapes of a tuned bladed disc. Moreover, a whole bladed disc finite element model (tubed and mistuned) has been created to investigate the effect of anisotropic material orientations on the forced responses of a mistuned bladed disc of a gas turbine. Finally, 2D and 3D response charts have been plotted for different cases to analyse the variation of the natural frequency of a single blade and a tuned bladed disc respectively due to the variation of anisotropic orientations of the blade material. Also, normalised forced responses of the mistuned bladed disc with four different mistuning patterns have been plotted against a number of blades of the whole bladed disc.
The outcome of these analyses indicates that the material anisotropy has a significant effect on the dynamic properties of a gas turbine bladed disc. In the case of a single blade, maximum frequency variation due to material anisotropy is found to be 5.3 % among the analysed cases. For tuned bladed disc, maximum frequency variation is found to be 5.1 % amongst the examined cases. Also, a discussion has been accomplished in terms of how Eulerian angles (primary and secondary angles) affects the natural frequency variations for different analysed cases of anisotropic orientations. Furthermore, amplification factor or normalised maximum forced responses are found to be within the range of 0.66 to 1.85 for the investigated cases of mistuned bladed disc with monocrystalline anisotropic blade material.

Item Type: Thesis (Masters)
Keywords: Blisk, Dynamics, Anisotropy, Monocrystalline blades, Mistunning, Modal Analysis, Harmonic Analysis
Schools and Departments: School of Engineering and Informatics > Engineering and Design
Research Centres and Groups: Dynamics, Control and Vehicle Research Group
Depositing User: Mr. Dibakor Boruah
Date Deposited: 03 Apr 2017 14:46
Last Modified: 04 Apr 2017 06:04
URI: http://sro.sussex.ac.uk/id/eprint/60870

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