On the modelling of hybrid aerostatic-gas journal bearings

Morosi, Stefano; Santos, Ilmar

doi:10.1177/1350650111399845

Cited by 29 publications

(31 citation statements)

References 11 publications

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“…A turbine (1) drives a flexible shaft (2), which is supported by both a ball bearing (3) and the controllable gas bearing (4) with four piezoactuated injectors. A disc (5) is mounted in one end to preload the journal and displacement sensors (6) measure the lateral movement of the disc in the shown reference frame.…”

Section: Test Rig Dimensionmentioning

confidence: 99%

Modelling and identification for control of gas bearings

Theisen

Niemann

Santos

et al. 2016

Mechanical Systems and Signal Processing

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Gas bearings are popular for their high speed capabilities, low friction and clean operation, but suffer from poor damping, which poses challenges for safe operation in presence of disturbances. Enhanced damping can be achieved through active lubrication techniques using feedback control laws. Such control design requires models with low complexity, able to describe the dominant dynamics from actuator input to sensor output over the relevant range of operation. The mathematical models based on first principles are not easy to obtain, and in many cases, they cannot be directly used for control design due to their complexity and parameter uncertainties. As an alternative, this paper presents an experimental technique for "in situ" identification of low complexity models of the entire rotor-bearingactuator system. Using grey-box identification techniques, the approach is shown to be easily applied to industrial rotating machinery with gas bearings and to allow for subsequent control design. The paper shows how piezoelectric actuators in a gas bearing are efficiently used to perturb the gas film for identification over relevant ranges of rotational speed and gas injection pressure. Parameter-varying linear models are found to capture the dominant dynamics of the system over the range of operation. Based on the identified models, decentralised proportional control is designed and is shown to obtain the required damping in theory as well as in a laboratory test rig.

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Section: Test Rig Dimensionmentioning

confidence: 99%

Modelling and identification for control of gas bearings

Theisen

Niemann

Santos

et al. 2016

Mechanical Systems and Signal Processing

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“…Control of active radial gas bearings by means of piezoelectric actuation is an interesting subject that can significantly extend gas bearing technology in the framework of industry 4.0. Until recently all multiphysical mathematical models derived based on the first principles, linking fundamental equations coming from the fields of rotordynamics, fluid dynamics, material science and control techniques, presented considerable deviations from experimental results, as it can be concluded from [1][2][3][4][5]. Not long ago there wasn't any proper models available for control design of active radial gas bearings via piezoelectric actuation.…”

Section: Introductionmentioning

confidence: 99%

Parametric Fault Diagnosis of an Active Gas Bearing

Sekunda

Niemann

Poulsen

et al. 2019

Int. J. Control Autom. Syst.

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Recently research into active gas bearings has had an increase in popularity. There are several factors that can make the use of gas bearings favourable. Firstly gas bearings have extremely low friction due to the usage of gas as the lubricant which reduce the needed maintenance. Secondly gas bearings is a clean technology which makes it possible to use for food processing, air condition and applications with similar requirements. Active gas bearings are therefore useful for applications where downtime is expensive and dirty lubricants such as oil are inapplicable. In order to keep as low downtime as possible it is important to be able to determine when a fault occurs. Fault diagnosis of active gas bearings is able to minimize the necessary downtime by making certain the system is only taken offline when a fault has occurred. Usually industry demands the removal of any sensor redundancy in systems. This makes it impossible to isolate faults using passive fault diagnosis. Active fault diagnosis methods have been shown able to isolate faults when there is no sensor redundancy. This makes active fault diagnosis methods relevant for industrial systems. It is in this paper shown possible to apply active fault diagnosis to diagnose parametric faults on a controllable gas bearing. The fault diagnosis is based on a statistical detector which is able to quantify the quality of the diagnosis scheme.

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“…Rotor dynamic characteristics are the key of stable operation of ACM, which reflect rotor response features and support characteristics of gas bearings. Morosi [14] presented a detailed mathematical model for hybrid lubrication of a compressible fluid-film journal bearing and built a multibody dynamics model of a global system comprising rotor and hybrid journal bearing to study the lateral dynamics of the system by Campbell diagrams and stability maps. Luis and Ryu [15] propose one way of restraining the critical speed region amplitude by changing the bearing supply gas pressure.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Characteristics of Air Cycle Machine Rotor System

Han

Long

Yang

2018

Shock and Vibration

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Parameters optimization in the critical speed region has the important influence on operational stability of an air cycle machine. Effects of bearing stiffness and unbalanced exciting force on critical speed and response characteristics are investigated by the modal method and harmonic response analysis. Resonance separation phenomenon in the critical speed region is analyzed in detail. When difference exists in the phase of unbalanced exciting force, resonance separation appears in the conical whirling speed region. The characteristics after resonance separation are closely related to the phase difference value and amplitude of unbalanced exciting force. The paper provides theoretical and experimental foundations for resonance separation analysis and also provides data support for dynamic balance and dynamic design of the rotor system.

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On the modelling of hybrid aerostatic-gas journal bearings

Cited by 29 publications

References 11 publications

Modelling and identification for control of gas bearings

Modelling and identification for control of gas bearings

Parametric Fault Diagnosis of an Active Gas Bearing

Dynamic Characteristics of Air Cycle Machine Rotor System

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