An investigation on the influence of the supporting structure on the dynamics of the rotor system

Cavalca, Kátia Lucchesi; Cavalcante, Paula Frassinetti; Okabe, Eduardo Paiva

doi:10.1016/j.ymssp.2004.04.001

Cited by 65 publications

(30 citation statements)

References 5 publications

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“…The rotor model adopted is a much stiffer version of the experimental model used by Cavalca et al in [19]. The rotor, which a sketch can be seen in Fig.…”

Section: Simulationmentioning

confidence: 99%

Rotordynamic analysis of systems with a non-linear model of tilting pad bearings including turbulence effects

Okabe

Cavalca

2008

Nonlinear Dyn

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An analytical model of a tilting pad bearing was developed based on the short bearing assumption with the turbulence effect included. In order to determine its influence on the dynamic behavior of the rotor, this model was compared against one without the turbulence effect through a simulation of a Jeffcott/Laval rotor supported by a couple of bearings. Both models were also used to determine the influence of geometric parameters on tilting pad bearing making use of the aforementioned system at different rotor speeds.When analyzing the results, the parameters which presented the largest influence were: pad preload, number of segments, radial clearance, pad position, and pad pivoting angle. As the pad moment of inertia and the pivoting distance have changed the shaft motion only a few microns, their effects can be neglected. The bearing model with turbulent flow effect has generated higher hydrodynamic forces when compared to the one without this effect, which remarks the importance of considering such phenomenon during the analysis of the high speed hydrodynamic bearings.

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“…The rotor model adopted is a much stiffer version of the experimental model used by Cavalca et al in [19]. The rotor, which a sketch can be seen in Fig.…”

Section: Simulationmentioning

confidence: 99%

Rotordynamic analysis of systems with a non-linear model of tilting pad bearings including turbulence effects

Okabe

Cavalca

2008

Nonlinear Dyn

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“…Edwards et al based on experimental equipment proposed an identification method for the flexible foundation parameters using run-up/run-down method [9][10][11]. Cavalca et al [12][13][14] developed a methodology of using mixed co-ordinate method to analyze the influence of the foundation structure on the rotor-bearing system on the base of experimental test rig with plate type foundation on flexible springs. The calculation model used by the authors was theoretical for the rotor and supports but for the foundation structure it was improved based on experimental results.…”

Section: Recent Methods For Foundation Structure Modelingmentioning

confidence: 99%

“…Nicolas et al [4,5], Cavalca et al . [12][13][14], Gasch [21], Stephenson and Rouch [22], Vance and Murphy [23]) and methods which use vibration data from the rotor or foundation structure during rundown or run-up of the whole system (e.g. Edwards et al [9][10][11], Feng and Hahn [17,18]).…”

Section: Recent Methods For Foundation Structure Experimental Testingmentioning

confidence: 99%

Theoretical Modeling for a Rotor-Bearing-Foundation System and Its Dynamic Characteristics Analysis

Hong

Shaposhnikov

Zhang

et al. 2015

Proceedings of the 9th IFToMM International Conference on Rotor Dynamics

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Modeling for rotor-bearing-foundation systems is one of the key bases for efficient dynamic analysis in the field of turbomachinery. However it should be noted that the term foundation structure should be interpreted depending on the purpose of the rotating machine. Thus in heavy power machinery it is usually a massive fixed base structure made of steel frames and concrete e.g. for power generating turbine units, but in aerospace it is relatively light and flexible beam type wing for aircraft engines. Since rotating machinery such as modern aircraft engines usually designed, marketed and sold for the most part based on analytical and numerical predictions, methods to incorporate the foundation influence effect in rotordynamic calculations are very important. The aim of the current paper is to observe recent efficient approaches for foundation structure modeling and to point out contemporary methods used by engineers for foundation structure parameters identification. Further in the simulation section of the paper simplified models were created in modern FEM software packages in order to demonstrate foundation structure influence on the dynamics of rotor-bearing system and their interaction.

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“…A finite element model (FEM) is often used to describe the mechanical properties of the shaft-train, while the dynamic effects caused by seals, fluid-film journal bearings and rolling bearings can be modeled by means of dynamic stiffness coefficients that may depend on the shaft rotating speed. In the end, machine casings, supports and foundation structure can be modeled by means of well known different techniques [22][23][24][25] here not described in detail for the sake of brevity.…”

Section: Definition Of the Instability Factor And Of The Analysis Crimentioning

confidence: 99%

Analysis of the Instability Phenomena Caused by Steam in High-Pressure Turbines

Pennacchi

Vania

2011

Shock and Vibration

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Abstract. Instability phenomena in steam turbines may happen as a consequence of certain characteristics of the steam flow as well as of the mechanical and geometrical properties of the seals. This phenomenon can be modeled and the raise of the steam flow and pressure causes the increase of the cross coupled coefficients used to model the seal stiffness. As a consequence, the eigenvalues and eigenmodes of the mathematical model of the machine change. The real part of the eigenvalue associated with the first flexural normal mode of the turbine shaft may become positive causing the conditions for unstable vibrations. The original contribution of the paper is the application of a model-based analysis of the dynamic behavior of a large power unit, affected by steam-whirl instability phenomena. The model proposed by the authors allows studying successfully the experimental case. The threshold level of the steam flow that causes instability conditions is analyzed and used to define the stability margin of the power unit.

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An investigation on the influence of the supporting structure on the dynamics of the rotor system

Cited by 65 publications

References 5 publications

Rotordynamic analysis of systems with a non-linear model of tilting pad bearings including turbulence effects

Rotordynamic analysis of systems with a non-linear model of tilting pad bearings including turbulence effects

Theoretical Modeling for a Rotor-Bearing-Foundation System and Its Dynamic Characteristics Analysis

Analysis of the Instability Phenomena Caused by Steam in High-Pressure Turbines

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