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Turbomachine blade vibration
01 Jan 1991-
TL;DR: In this paper, the authors present a detailed analysis of single and coupled blade-disc vibrations, as well as the effect of small aspect ratio on the number of vibrations.
Abstract: Single Blade Vibrations Discrete Analysis of Blades Small Aspect Ratio Blades Blade Group Frequencies and Mode Shapes Excitation Damping Forced Vibrations Transient Vibrations Coupled Blade-Disc Vibrations Some Thoughts on Fatigue Life Estimation Some Reflections Appendices: Heat Transfer and Thermal Stress of Turbine Blades SI Units Nomenclature Index.
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01 Jan 2003
TL;DR: In this article, the rotating mode shapes of flexible shrouded bladed disc-shaft assemblies are calculated by using a finite element cyclic symmetry approach and all possible couplings between the flexible parts are allowed.
Abstract: It is now increasingly necessary to predict accurately, at the design stage and without excessive computer costs, the dynamic behaviour of rotating parts of turbomachines, in order to avoid resonant conditions at operating speeds. In this study, the global rotating mode shapes of flexible shrouded bladed disc-shaft assemblies are calculated. The rotating modes are calculated by using a finite element cyclic symmetry approach. Rotational effects, such as centrifugal stiffening are accounted for, and all the possible couplings between the flexible parts are allowed. The gyroscopic effects are neglected. The numerical results were compared with the experimental. The calculation shows the influence of the shaft flexibility on the natural frequencies of the shrouded bladed discs up to four nodal diameters for two first frequencies series.
TL;DR: In this paper, the resonance frequencies and vibration modes of a gas turbine blade having a transpiration cooling system made in the form of a set of rectilinear pores are analyzed.
Abstract: Matters relating to application of the theory of saturated porous media for analyzing the dynamic characteristics of structural elements of power equipment are considered. Calculations of the resonance frequencies and vibration modes of a gas turbine blade having a transpiration cooling system made in the form of a set of rectilinear pores are presented.
Cites background from "Turbomachine blade vibration"
...Quite a large number of papers on heat transfer in porous thermal–mechan� ical constructions have already been published [2, 3]. However, it is well known that the conditions under which rotor equipment operate are characterized not only by high temperatures of working fluid, but also by variable stresses due to high�frequency vibration and centrifugal forces [ 4 ]....
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TL;DR: In this article, a design modification is made on the 9th stage wheel dovetail of a high-intermediate pressure (HIP) turbine rotor for a 500 MW fossil power plant that necessitates the use of new long-shank buckets for the row.
Abstract: Vibration test and analysis results of running buckets are presented. A design modification is made on the 9th stage wheel dovetail of a high-intermediate pressure (HIP) turbine rotor for a 500 MW fossil power plant that necessitates the use of new long-shank buckets for the row. A bucket vibration test is necessary to verify whether the new 9-th stage buckets have adequate frequency margin from a nozzle passing frequency when running at speed. A finite element analysis (FEA) has been performed using commercial S/W to approximately estimate the difference between the modified and the normal bucket natural frequencies at various rotational speeds. After a row of the new buckets has been assembled on the HIP rotor for the vibration tests using dynamic balancing facilities, deceleration tests have been conducted. The test results are compared with the FEA and our empirical formulas, and show that the modified design meets the frequency-margin requirements.
01 Jan 2004
TL;DR: In this paper, an open cylindrical panel, which has a twist around the lengthways direction and double curvature in the radial and lengthways directions, is a better shell model of some turbine blades.
Abstract: Summary An open cylindrical panel, which has a twist around the lengthways direction and double curvature in the radial and lengthways directions, is a better shell model of some turbine blades. For the sake of high accuracy of a vibration analysis method, a precise relationship between strains and displacement components of the shell model is derived on the general shell theory and the first order shear deformation theory. By using the principle of virtual work and the Rayleigh-Ritz method, the governing equation for free vibration of the model is presented. The effects of parameters such as curvature and twist on vibration are studied.
01 Oct 2000
TL;DR: In this paper, the bending vibrations of a rotating non-uniform composite Timoshenko beam with attachment and elastically restrained root are studied and the influence of lamination angle, rotating speed, setting angle, hub radius, tip mass, taper ratio and elastic root restraints on the rotating instability phenomenon is investigated.
Abstract: The bending vibrations of a rotating non-uniform composite Timoshenko beam with attachment and elastically restrained root are studied. The beam considered is an inextensional laminated angle ply structure with doubly symmetric cross section such that the centroidal axis and the neutral axis are coincident. It is a common concept that the natural frequencies of a rotating beam will increase as the rotating speed is increased. However, this is not the case for the rotating beam with setting angle and elastically restrained root. A dynamic instability due to rotating, namely rotating instability phenomenon (divergence instability) may occur. The influence of lamination angle, rotating speed, setting angle, hub radius, tip mass, taper ratio and elastic root restraints on the rotating instability phenomenon is investigated.