Unbalance Behavior of Squeeze Film Damped Multi-Mass Flexible Rotor Bearing Systems

McLean, L. J.; Hahn, E. J.

doi:10.1115/1.3254538

Cited by 36 publications

(17 citation statements)

References 8 publications

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“…In this case, the continuous rotor model is discretized and a finite number of DOFs are introduced. The dynamics of multi-mass and multi-degrees of freedom (MDOF) rotors supported with SFDs is theoretically studied in [43,44]. The precedent studies assumed that the effect of lubricant inertia on the fluid film reaction forces in SFDs is negligible and either used the complete or the approximate (i.e., long bearing and short bearing approximations) Reynolds equation to represent the SFD dynamics.…”

Section: Introductionmentioning

confidence: 99%

A Study of Lubricant Inertia Effects for Squeeze Film Dampers Incorporated into High-Speed Turbomachinery

Hamzehlouia

Behdinan

2017

Lubricants

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This work proposes a numerical model that incorporates the effect of lubricant inertia on the hydrodynamic pressure distribution, fluid film reaction forces, and the fluid velocity component profiles for finite-length open-ended squeeze film dampers (SFDs). Firstly, the thin film flow equations for the SFD in presence of fluid inertia effects are introduced. Furthermore, a small first-order perturbation by means of the expressions for the fluid film velocity components and the lubricant pressure distribution that are expanded in power series of the squeeze film Reynolds number is applied to the flow equations. Subsequently the developed lubricant flow equations are solved to develop expressions for the velocity component profiles and the hydrodynamic pressure distribution in SFDs. The pressure expression is numerically solved by using Gauss-Seidel method with finite difference discretization. Moreover, the fluid film reaction forces are determined by numerically integrating the hydrodynamic pressure expressions over the journal surface. Additionally, the proposed pressure distribution expression and the numerical SFD forces are incorporated into a simulation model and the simulation results are compared with the existing models in the literature under different operating conditions, including eccentricity ratios and inertia effects (i.e., Reynolds numbers). The simulation results demonstrate the significant influence of both convective and temporal (i.e., unsteady) lubricant inertia terms on the SFD hydrodynamic pressure distribution and the fluid film reaction forces. Furthermore, the proposed SFD model is incorporated into a multi-mass flexible rotordynamic model to evaluate the effect of SFD fluid inertia on the mass unbalance induced steady-state vibrations of the rotor and the nodal transient orbits by implementing finite element method and transient modal integration with predictor-corrector solver. The results of the analysis demonstrate the significant effect of fluid inertia on the resonance frequencies of the rotor and the steady-state vibration amplitudes and the transient orbits at the resonance zone.

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Section: Introductionmentioning

confidence: 99%

A Study of Lubricant Inertia Effects for Squeeze Film Dampers Incorporated into High-Speed Turbomachinery

Hamzehlouia

Behdinan

2017

Lubricants

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“…On the contrarily, if p is the solution of the free boundary problem (15), then (17) gives the variational equation (14); and again, in the limit 0 ≤ q ∈ K ⊂ H 1 0 (Ω), (16) gives the variational inequality (13).…”

Section: Fundamental Theorem For Nonlinear Forces Of Bearingsmentioning

confidence: 99%

“…Several publications [7,16,17], deal with the order reduction methods of complex rotor-bearing system. But almost all the order reduction methods do not consider the effect of nonlinear oil-film force when forming transformation matrices.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear modeling and dynamic analysis of the rotor-bearing system

et al. 2008

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To overcome the shortcomings of extreme time-consuming in solving the Reynolds equation, two efficient calculation methods, based on the free boundary theory and variational principles for the unsteady nonlinear Reynolds equation in the condition of Reynolds boundary, are presented in the paper. By employing the two mentioned methods, the nonlinear dynamic forces as well as their Jacobians of the journal bearing can be calculated saving time but with the same accuracy. Of these two methods, the one is called a Ritz model which manipulates the cavitation region by simply introducing a parameter to match the free boundary condition and, as a result, a very simple approximate formulae of oil-film pressure is being obtained. The other one is a one-dimensional FEM method which reduces the two-dimensional variational inequality to the one-dimensional algebraic complementary equations, and then a direct method is being used to solve these complementary equations, without the need of iterations, and the free boundary condition can be automatically satisfied. Meanwhile, a new order reduction method is contributed to reduce the degrees of freedom of a complex rotor-bearing system. Thus the nonlinear behavior analysis of the rotorbearing system can be studied time-sparingly. The results in the paper show the high efficiency of the two methods as well as the abundant nonlinear phenomenon of the system, compared with the results obtained by the usual numerical solution of the Reynolds equation.

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“…For squeeze film dampers with retaining springs, much theoretical and experimental work has been done under the assumption of a synchronous and circular rotor motion (White, 1972;Mohan and Hahn, 1974;Feng, 1988;McLean and Hahn, 1983). In this special case, the solution procedure was reduced to the solution of a single nonlinear algebraic equation.…”

Section: Introductionmentioning

confidence: 99%

Stability and Bifurcation of Unbalanced Response of a Squeeze Film Damped Flexible Rotor

Zhao

Linnett

McLean³

1994

Journal of Tribology

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The stability and bifurcation of the unbalance response of a squeeze film dampermounted flexible rotor are investigated based on the assumption of an incompressible lubricant together with the short bearing approximation and the "it "film cavitation model. The unbalanced rotor response is determined by the trigonometric collocation method and the stability of these solutions is then investigated using the Floquet transition matrix method. Numerical examples are given for both concentric and eccentric damper operations. Jump phenomenon, subharmonic, and quasi-periodic vibrations are predicted for a range of bearing and unbalance parameters. The predicted jump phenomenon, subharmonic and quasi-periodic vibrations are further examined by using a numerical integration scheme to predict damper trajectories, calculate Poincare maps and power spectra. It is concluded that the introduction of unpressurized squeeze film dampers may promote undesirable nonsynchronous vibrations.

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Unbalance Behavior of Squeeze Film Damped Multi-Mass Flexible Rotor Bearing Systems

Cited by 36 publications

References 8 publications

A Study of Lubricant Inertia Effects for Squeeze Film Dampers Incorporated into High-Speed Turbomachinery

A Study of Lubricant Inertia Effects for Squeeze Film Dampers Incorporated into High-Speed Turbomachinery

Nonlinear modeling and dynamic analysis of the rotor-bearing system

Stability and Bifurcation of Unbalanced Response of a Squeeze Film Damped Flexible Rotor

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