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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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TL;DR: In this paper, the spectral-Tchebychev (ST) technique is used to solve the integral boundary value problem for rotating structures, including those with complex geometries and mixed boundary conditions.
44 citations
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TL;DR: In this paper, the origin of tip vortices is explained and the technological relevance of tip vortex behavior is reviewed. And the authors summarize lifting line theory, the simplest finite wing theory, and synopsizes our knowledge of the tip vortex behaviour.
Abstract: One of the most conspicuous features of an airplane flying at high altitude is its white contrails. These contrails, which are formed by the condensation of engine exhaust water vapour, clearly delineate the location of the wing tip vortices. The contrails are often the first — and perhaps the only — exposure most of us have to wing tip vortices (also referred to as “trailing vortices” or, imprecisely, as “wing wake vortices” or “tip wake vortices”). This chapter aims to explain the origin of tip vortices (§X.l) and review their technological relevance (§X.2). The chapter then summarizes lifting line theory, the simplest finite wing theory (§X.3), and synopsizes our knowledge of tip vortex behaviour (§X.4, §X.5).
42 citations
TL;DR: A hybrid approach comprising a stochastic Finite Element Model (FEM) based modal analysis and Bayesian Linear Regression (BLR) based BTT technique is proposed and used for the identification and classification of turbomachine blade damage.
41 citations
Cites background from "Turbomachine blade vibration"
...Synchronous blade vibrations occur as an Engine Order (EO) of the shaft rotational speed and is generally a result of the fluid-flow path being obstructed by a multiplicity of structural components [10]....
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TL;DR: In this paper, an exact power-series solution for free vibration of a rotating inclined Timoshenko beam was developed, and it was shown that both the extensional deformation and the Coriolis force will have significant influence on the natural frequencies of the rotating beam when the dimensionless rotating extension parameter is large.
40 citations
TL;DR: In this paper, the boundary conditions for the coupled bending-bending-extensional vibration of a rotating nonuniform beam with arbitrary pretwist and an elastically restrained root are derived by Hamilton's principle.
Abstract: The governing differential equations and the boundary conditions for the coupled bending-bending-extensional vibration of a rotating nonuniform beam with arbitrary pretwist and an elastically restrained root are derived by Hamilton’s principle. The semianalytical solution procedure for an inextensional beam without taking account of the coriolis forces is derived. The coupled governing differential equations are transformed to be a vector characteristic governing equation. The frequency equation of the system is derived and expressed in terms of the transition matrix of the vector governing equation. A simple and efficient algorithm for determining the transition matrix of the general system with arbitrary pretwist is derived. The divergence in the Frobenius method does not exist in the proposed method. The frequency relations between different systems are revealed. The mechanism of instability is discovered. The influence of the rotatory inertia, the coupling effect of the rotating speed and the mass moment of inertia, the setting angle, the rotating speed and the spring constants on the natural frequencies, and the phenomenon of divergence instability are investigated. @DOI: 10.1115/1.1408615#
38 citations