Analysis of the Journal Bearing Friction Losses in a Heavy-Duty Diesel Engine

Knauder, Christoph; Allmaier, Hannes; Sander, David Emanuel; Salhofer, Stefan; Reich, Franz Markus; Sams, Theodor

doi:10.3390/lubricants3020142

Cited by 40 publications

(21 citation statements)

References 22 publications

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“…Therefore, the viscosity is also a function of shear rateγ. The following combination of the Vogel and the Cross equation is a suitable description of the oil viscsosity function in this case [17]:…”

Section: Oilmentioning

confidence: 99%

Rotordynamic and Friction Loss Measurements on a High Speed Laval Rotor Supported by Floating Ring Bearings

et al. 2017

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Abstract:Floating ring bearings are the commonly used type of bearing for automotive turbochargers. The automotive industry continuously investigates how to reduce the bearing friction losses and how to create silent turbochargers. Many of these studies involve creating a numerical model of the rotor-bearing system and performing validation on a test bench on which a turbocharger is driven by hot gases. This approach, however, involves many uncertainties which diminish the validity of the measurement results. In this study, we present a test setup in which these uncertainties are minimized. The measurement results show the behavior of the floating ring bearing as a function of oil feed pressure, oil feed temperature, rotor unbalance and bearing clearances. Next to an increased validity, the test setup provides measurement data with good repeatability and can therefore represent a case study which can be used for validation of rotor-bearing models.

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Section: Oilmentioning

confidence: 99%

Rotordynamic and Friction Loss Measurements on a High Speed Laval Rotor Supported by Floating Ring Bearings

et al. 2017

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“…Energy equation, fluid domain: In the present work, the utilized values of thermophysical properties for the lubricant are given in Table 2. In particular, a 5W30 lubricant is assumed, characterized by a density value of 855 kg/m 3 , whereas the rheological properties of the lubricant are described using the Vogel equation for the dependence of viscosity on temperature T and the Cross equation to describe the shear-rate influence on viscosity, according to the following relation [10]:…”

Section: Numerical Modelmentioning

confidence: 99%

“…Depending on the operating conditions and the design of the bearing system, the thrust bearing may be responsible for roughly half of the total friction losses of the bearing system [7,9]. Therefore, the friction losses of turbocharger thrust bearings have already been studied extensively [7][8][9][10][11][12][13][14].…”

mentioning

confidence: 99%

Design Optimization of an Automotive Turbocharger Thrust Bearing Using a CFD-Based THD Computational Approach

et al. 2018

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In a quest to reduce fuel consumption and emissions of automotive combustion engines, friction losses from many different sources need to be minimized. For modern designs of turbochargers commonly used in the automotive industry, reduction of friction losses results in better efficiency and also contributes to a faster transient response. The thrust bearing is one of the main contributors to the mechanical losses of a turbocharger. Therefore, it is crucial to optimize the design of the thrust bearing so that it has minimum friction losses while keeping sufficient thrust carrying capacity. One of the main challenges of turbocharger thrust bearing design, is that rotation speed is not fixed: the turbocharger may have a rotation speed which varies between 0 to as much as 250 kRPM. Moreover, the thrust bearing generates considerable heat, which changes the temperature of the oil film and its surroundings. In the present work, the design of the thrust bearing of an automotive turbocharger has been optimized. A CFD-based Thermohydrodynamic (THD) computational approach has been developed, taking into consideration heat dissipation, conjugate heat transfer throughout the bearing domain including the surrounding parts, as well as shear thinning and cavitation in the lubricant domain. An optimizer has been coupled to the CFD solver, with the aim of identifying bearing designs with reduced friction losses. Two bearing concepts have been evaluated: a taper-land design-which is a commonly applied thrust bearing concept-as well as a pocket bearing design. The resulting optimum pocket designs exhibit improved performance, in comparison to the optimum taper-land design. The present results indicate that (a) the pocket design concept can substantially contribute to further reducing the friction losses of a turbocharger, and (b) optimal design parameters of pocket bearings depend on the specific application (size, operating conditions), therefore detailed calculations should be performed to verify optimum performance.

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“…This non-Newtonian effect is often referred to as shear thinning [4]. In Model 3, the viscosity formulation of Model 2 is therefore extended by including shear rate dependency according to the Cross equation [25]:…”

Section: Rotor Parametersmentioning

confidence: 99%

Towards Accurate Prediction of Unbalance Response, Oil Whirl and Oil Whip of Flexible Rotors Supported by Hydrodynamic Bearings

et al. 2016

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Journal bearings are used to support rotors in a wide range of applications. In order to ensure reliable operation, accurate analyses of these rotor-bearing systems are crucial. Coupled analysis of the rotor and the journal bearing is essential in the case that the rotor is flexible. The accuracy of prediction of the model at hand depends on its comprehensiveness. In this study, we construct three bearing models of increasing modeling comprehensiveness and use these to predict the response of two different rotor-bearing systems. The main goal is to evaluate the correlation with measurement data as a function of modeling comprehensiveness: 1D versus 2D pressure prediction, distributed versus lumped thermal model, Newtonian versus non-Newtonian fluid description and non-mass-conservative versus mass-conservative cavitation description. We conclude that all three models predict the existence of critical speeds and whirl for both rotor-bearing systems. However, the two more comprehensive models in general show better correlation with measurement data in terms of frequency and amplitude. Furthermore, we conclude that a thermal network model comprising temperature predictions of the bearing surroundings is essential to obtain accurate predictions. The results of this study aid in developing accurate and computationally-efficient models of flexible rotors supported by plain journal bearings.

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Analysis of the Journal Bearing Friction Losses in a Heavy-Duty Diesel Engine

Cited by 40 publications

References 22 publications

Rotordynamic and Friction Loss Measurements on a High Speed Laval Rotor Supported by Floating Ring Bearings

Rotordynamic and Friction Loss Measurements on a High Speed Laval Rotor Supported by Floating Ring Bearings

Design Optimization of an Automotive Turbocharger Thrust Bearing Using a CFD-Based THD Computational Approach

Towards Accurate Prediction of Unbalance Response, Oil Whirl and Oil Whip of Flexible Rotors Supported by Hydrodynamic Bearings

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