Active lubrication applied to radial gas journal bearings. Part 1: Modeling

Morosi, Stefano; Santos, Ilmar

doi:10.1016/j.triboint.2011.08.007

Cited by 81 publications

(57 citation statements)

References 20 publications

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“…Mechatronic systems are an attractive active solution where electromechanical actuators are embedded into the bearings with advanced control systems. A promising design solution is the controllable gas bearing where pressurised air is injected through piezo-actuators [4,6,7]. Active gas bearings are attractive for a number of applications including compressors, atomisers and turbochargers, but the bearing development is still in its early stage.…”

Section: Literature Surveymentioning

confidence: 99%

“…To achieve robustness of the control system the availability of dynamical models and uncertainty descriptions are of paramount importance. Due to the multi-physics nature of the system high-fidelity models as those presented in [4,9] result in large dimensionality (model order higher than hundred), which is generally unsuitable for control system design. Therefore an alternative approach has been explored in [7], where a linear parameter-varying (LPV) identification method was applied to identify low-complexity models of the entire rotor-bearing actuator-sensor system.…”

Section: Literature Surveymentioning

confidence: 99%

See 1 more Smart Citation

Enhancing damping of gas bearings using linear parameter-varying control

Theisen

Niemann

Galeazzi

et al. 2017

Journal of Sound and Vibration

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a b s t r a c tJournal bearings can be lubricated through controllable injectors using pressurised fluids, whose viscosity highly determines the dynamic responses of the rotating machine. The use of fluids with low viscosity is attracting a growing interest due to the reduced friction forces and consequent losses when the machine is in operation. However low viscosity also entails poor damping properties, which may lead to degraded performance or even instability when the rotating machine operates at or near one of the modal frequencies. This issue can be properly addressed by employing active feedback control systems to regulate the injection pressure of the fluid. Due to the strong dependencies of system performance on system parameters, the sought controller should be robust over a large range of operational conditions. This paper addresses the damping enhancement of controllable gas bearings through robust control approaches. Through an extensive experimental campaign the paper evaluates two robust controllers, a linear parametervarying (LPV) controller and ∞  controller, on their capability to guarantee stability and performance of a gas bearing across the large operational envelopes in rotational speed and injection pressure. The control systems are designed applying state-of-the-art methods in the respective areas. The experimental results clearly demonstrate the feasibility of enhancing the damping properties of a gas bearing by means of robust control methods.

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Section: Literature Surveymentioning

confidence: 99%

Section: Literature Surveymentioning

confidence: 99%

Enhancing damping of gas bearings using linear parameter-varying control

Theisen

Niemann

Galeazzi

et al. 2017

Journal of Sound and Vibration

Self Cite

View full text Add to dashboard Cite

show abstract

“…An approach presented in [13] uses a nonlinear state space model with states being position, and velocity of the piezo ceramic, and pressure in the chamber between the journal and bearing housing. The mentioned model however contains a coupling to the pressure of the lubricant, which in this case is not measured, making it challenging to use.…”

Section: Experimental Identification Of Gas Bearing Parametersmentioning

confidence: 99%

“…The Reynolds equation is solved to obtain a pressure distribution, which is integrated to obtain the aerodynamic forces. An input-output-model (IO model) was developed in [13] using a first order principles model to incorporate the behaviour of the piezo-electric valves into the Reynolds equation. This model catches well the behaviour of the bearing over a wide range of parameters but has too high complexity to be directly used for model based control.…”

Section: Introductionmentioning

confidence: 99%

Experimental Grey Box Model Identification and Control of an Active Gas Bearing

Theisen

Pierart

Niemann

et al. 2014

Mechanisms and Machine Science

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Gas bearings have inherent dynamics that gives rise to low damping and potential instability at certain rotational speeds. Required damping and stabilization properties can be achieved by active flow control if bearing parameters are known. This paper deals with identification of parameters in a dynamic model of an active gas bearing and subsequent control loop design. A grey box model is determined based on experiments where piezo actuated valves are used to perturb the journal and hence excite the rotor-bearing system. Such modelling from actuator to output is shown to efficiently support controller design, in contrast to impact models that focus on resonance dynamics. The identified model is able to accurately reproduce the lateral dynamics of the rotor-bearing system in a desired operating range, in this case around the first two natural frequencies. The identified models are validated and used to design a model-based controller capable of improving the damping of the gas bearing. Experimental impact responses show an increase in damping by a factor nine for the investigated conditions.

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“…Morosi [14] presented a detailed mathematical model for hybrid lubrication of a compressible fluid-film journal bearing, and built a multi-body dynamics model of a global system comprised of rotor and hybrid journal bearing to study the lateral dynamics of the system by Campbell diagrams and stability maps. They explored the feasibility of applying active lubrication to gas journal bearings by mechatronic system with the pneumatic and dynamic characteristics of a piezoelectric actuated valve system [15].…”

Section: Introductionmentioning

confidence: 99%

Experimental investigations on effects of axial clearance on high-speed turbine expansion generator rotor response

Han¹,

Yang²,

Wang³

2017

J. vibroeng.

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Bearing-rotor system dynamic characteristic is the key influence on high-speed power equipment stability. The experimental investigations focus on the dynamic characteristics of highspeed turbine expansion generator rotor, which was supported by gas aerostatic bearings. Nonlinear dynamic behavior of high-speed turbine expansion generator rotor, including gas film whipping and gas film half-speed whirling, were analyzed in the experiments. Static characteristic tests for effects of bearing supply gas pressure on the bearing axial clearance are carried out to provide the rotor axial position under different bearing supply gas pressure groups, which showed that the bearing thrust performance changed with bearing supply gas pressure. The experimental results of rotor dynamic characteristics under different bearing supply gas pressure groups show that gas film whirling and whipping occurred in the mentioned bearing-rotor system during the speed up process when the axial clearance for two ends were different. The shafting stability under the same axial clearance for two ends is better than the condition under the different bearing axial clearance. The paper gives some measures to improve the high-speed bearing-rotor system stability.

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Active lubrication applied to radial gas journal bearings. Part 1: Modeling

Cited by 81 publications

References 20 publications

Enhancing damping of gas bearings using linear parameter-varying control

Enhancing damping of gas bearings using linear parameter-varying control

Experimental Grey Box Model Identification and Control of an Active Gas Bearing

Experimental investigations on effects of axial clearance on high-speed turbine expansion generator rotor response

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