The Damping Capacity of a Sealed Squeeze Film Bearing

Dede, Mehmet; Dogan, M.; Holmes, R.

doi:10.1115/1.3261097

Cited by 23 publications

(15 citation statements)

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“…short , long are the short and long bearing approximations respectively [25], , are spatial coordinates local to the oil film, L the land length and , are the polar coordinates of the instantaneous position of the journal centre relative to the instantaneous position of the bearing housing centre, that, along with their time derivatives ,̇, are calculated from ,̇ via the integrated state variables ( ), ̇( ) (eq. (2)).…”

Section: Overview Of Forward Problemmentioning

confidence: 99%

Improved non-invasive inverse problem method for the balancing of nonlinear squeeze-film damped rotordynamic systems

Cedillo

Al-Ghazal

Bonello

et al. 2019

Mechanical Systems and Signal Processing

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A non-invasive inverse problem method for rotor balancing relies on casing vibration readings and prior knowledge of the structure. Such a method is important for rotors that are inaccessible under operating conditions. This paper introduces a method for solving the quasi-implicit inverse problem that arises when identifying the required balancing correction for a rotor with only one weak linear connection to the casing, apart from the nonlinear connections. This is typical of aero-engine designs that use a retainer spring with only one of the nonlinear squeeze-film damper (SFD) bearings that support the rotor within the casing. The SFD journal displacements are estimated from casing vibration readings using identified inverse SFD models based on Recurrent Neural Networks (RNNs). The information from these is then used to enhance the condition of the explicit inverse problem set up in previous research for simpler configurations. The methodology is validated using simulated casing vibration readings. The reliability of the RNN inverse SFD models is first demonstrated. The second part of the validation shows that the novel enhanced explicit inverse problem method is essential for effective balancing of this previously unconsidered system. Repeatability and robustness to noise/model uncertainty are satisfactorily demonstrated and limitations discussed.The identification of the rotor unbalance from vibration measurements at the casing and/or the rotor is referred to as an "inverse" problem [3], in contrast to the "forward" problem, which refers to the prediction of the system vibration in response to a known unbalance distribution. Traditional balancing methods (which include the standard "trim" balancing procedures) [4][5][6][7][8] involve the use of several trial runs and the application of trial masses at fixed balancing planes. Such types of methods are typically based on two representative methods, the influence coefficients balancing method [5] and the modal balancing method [4]. Darlow [6] developed the Unified Balancing Approach (UBA) that combined the advantages of both previous methods. The UBA method involved the calculation of modal trial mass sets, based on the influence coefficient approach of using trial mass data. Foiles et al [7] provided a comprehensive review of the several direct methods for rotor balancing, which were based on the fundamentals of the influence coefficients method and modal method.Chen et al [9] proposed an optimisation technique based on nonlinear programming to determine the balancing corrections to be applied to prescribed planes. This method required a valid mathematical model of the rotor-dynamic system to use within the optimisation scheme. Unlike the methods of [4][5][6][7][8], the method of Chen et al [9] did not require several trial runs and trial masses since the optimisation was based on measurements from the initial (unbalanced) configuration. However, the method was still invasive since it required measurement of the vibration of the rotor. Moreover, the system ...

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Section: Overview Of Forward Problemmentioning

confidence: 99%

Improved non-invasive inverse problem method for the balancing of nonlinear squeeze-film damped rotordynamic systems

Cedillo

Al-Ghazal

Bonello

et al. 2019

Mechanical Systems and Signal Processing

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“…The use of the incompressible Reynolds equation means that the effects of compressibility due to air entrainment are not accounted for. Variable cavitation pressure is often observed in experiments [5,12], suggesting that air entrainment and therefore cavitation is dependent upon the bearing dynamics. Although attempts have been made to account for compressibility of the fluid film e.g.…”

Section: Introductionmentioning

confidence: 97%

“…Such one-dimensional analytical solutions are achieved by assuming that pressure gradients in one direction, either circumferential or axial, are negligible and are respectively named short and long bearing solutions. In the literature there are many variants of the long and short bearing approximations [4,5]. The most prominent of these variants involves the combination of the short and long pressure solutions through an empirical "end-leakage factor"  that accounts for the degree of end-sealing [5,6].…”

Section: Introductionmentioning

confidence: 99%

“…In the literature there are many variants of the long and short bearing approximations [4,5]. The most prominent of these variants involves the combination of the short and long pressure solutions through an empirical "end-leakage factor"  that accounts for the degree of end-sealing [5,6]. This model is popular with industry and was used recently for whole-engine analysis with 5 SFDs using IRM and RHBM [7].…”

Section: Introductionmentioning

confidence: 99%

“…As stated in [1], the factor  can only be related to the parameters of a given bearing when it is hosted in a given experimental setup. Attempts to theoretically relate it to the SFD parameters have proved unsuccessful [5]. Moreover, this  -model cannot account for the effect of the groove and feed-ports.…”

Section: Introductionmentioning

confidence: 99%

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An Investigation Into Two Alternative Approaches for the Identification of SFD Bearings for Aeroengine Analysis

Groves

Bonello

2011

Volume 6: Structures and Dynamics, Parts a and B

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Identification techniques provide a means of efficiently implementing complex nonlinear bearing models in practical turbomachinery applications. This paper considers both identification from an advanced numerical model and identification from experimental tests. Identification from numerical models is essential at the design stage, where rapid simulation of the dynamic performance of a variety of designs is required. Experimental identification is useful to capture effects that are difficult to model (e.g. geometric imperfections, compressibility and its effect on cavitation). With regard to identification from a numerical model, it was shown in a previous paper that the numerical solution of the incompressible Reynolds equation may be replicated using Chebyshev polynomial fits. Tests were performed on a simple rotor-bearing configuration incorporating an advanced numerical bearing model. The identified model was found to be able to match the accuracy of the numerical solution to the Reynolds equation while requiring a fraction of the computation time. In the present work the SFD identification scheme is applied to a realistically-sized representative wholeaeroengine model. It is shown that using recently introduced nonlinear solvers combined with the identified high accuracy bearing models it is possible to run full engine rotor-dynamic simulations, in both the time and frequency domains, at a fraction of the previous computational cost. One major drawback of the Chebyshev technique is that it is not amenable to experimental identification of actual bearings. For this reason, a second identification approach, involving the use of neural networks, is considered in this paper. A test rig that enables empirical identification of SFD forces has been constructed and details of the building and operation of the test rig is presented. The method used to ascertain the training data required by the neural network identification scheme, is also described. Downloaded From: http://proceedings.asmedigitalcollection.asme.org/ on 03/30/2015 Terms of Use: http://asme.org/terms y J J J J J y

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Mechanical and vibration characteristics investigation of the elastic ring squeeze film damper-rotor considering oil film sealing and leakage

Sun,

Luo,

et al. 2024

International Journal of Non-Linear Mechanics

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The Damping Capacity of a Sealed Squeeze Film Bearing

Abstract: The purpose of this paper is to establish a theoretical model to represent a sealed squeeze-film damper bearing and to assess it against results from a test rig, simulating the essential features of a medium-sized gas turbine aero engine.

Cited by 23 publications

References 0 publications

Improved non-invasive inverse problem method for the balancing of nonlinear squeeze-film damped rotordynamic systems

Improved non-invasive inverse problem method for the balancing of nonlinear squeeze-film damped rotordynamic systems

An Investigation Into Two Alternative Approaches for the Identification of SFD Bearings for Aeroengine Analysis

Mechanical and vibration characteristics investigation of the elastic ring squeeze film damper-rotor considering oil film sealing and leakage

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