Reduction of Power Losses in Bearing Chambers Using Porous Screens Surrounding a Ball Bearing

Flouros, Michael

doi:10.1115/1.1995769

Cited by 13 publications

(9 citation statements)

References 3 publications

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“…A similar situation was described also by Flouros [13], who conducted experiments in a beadng compartment using a ball beadng of an aero engine. He concluded that the amount of droplets generated by the hall beadng is reduced when using porous screens to surround the bearing.…”

Section: Cases Studiedmentioning

confidence: 64%

CFD Modeling and LDA Measurements for the Air-Flow in an Aero Engine Front Bearing Chamber

Aidarinis

Missirlis

Yakinthos

et al. 2011

Journal of Engineering for Gas Turbines and Power

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The continuous development of aero engines toward lighter but yet more compact designs, without decreasing their efficiency, has led to gradually increasing demands on the lubrication system, such as the bearing chambers of an aero engine. For this reason, it is of particular importance to increa.se the level of understanding of the flow fleld inside the bearing chamber in order to optimize its design and improve its performance. The flow field inside a bearing chamber is complicated since there is a strong interaction between the .sealing air-flow and the flow of lubrication oil, and both of them are affected by and interacting with the geometry of the chamber and the rotating shaft. In order to understand the flow field development and, as a next step, to optimize the aero engine bearing chamber performance, in relation to the lubrication and heat trari.sfer capabilities, the behavior of this interaction must be investigated. In this work, an investigation of the air-flow field development inside the front bearing chamber of an aero engine is attempted. The front bearing chamber is divided into two separate sections. The flow from the flrst section passes through the bearing and the bearing holding structure to the second one where the vent and the scavenging system are located. The investigation was performed with the combined use of experimental measurements and computational fluid dynamics (CFD) modeling. The experimental measurements were carried out using a la.ser Doppter anemometry system in an experimental rig, which consists of a 1:1 model of the front bearing chamber of an aero engine. Tests were carried out at real operating conditions both for the air-flow and for the lubricant oil-flow and for a range of shaft rotating speeds. The CFD modeling was performed using a commercial CFD package. Particularly, the air-fiow through the bearing itself was modeled, adopting a porous medium technique, the parameters of which were developed in conjunction with the experiments. A satisfactory quantitative agreement between the experimental measurements and the CFD computations was achieved. At the same time, the effect of the important parameters such as the air and oil mass flow, together with the shaft rotational speed, and the effect of the chamber geometry were identified. The conclusions can be e.xploited in future attempts in combination with the CFD model developed in order to optimize the efficiency of the lubrication and cooling system. The latter forms the main target of this work, which is the development of a useful engineering tool capable of predicting the fiow field inside the aero engine bearing, which can be used subsequently for optimization purposes.

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Section: Cases Studiedmentioning

confidence: 64%

CFD Modeling and LDA Measurements for the Air-Flow in an Aero Engine Front Bearing Chamber

Aidarinis

Missirlis

Yakinthos

et al. 2011

Journal of Engineering for Gas Turbines and Power

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“…[6], the impact of the screens on the reduction in parasitic losses in a bearing chamber was investigated. The results are displayed in Fig.…”

Section: Simulation Cases Cfd Modeling and Resultsmentioning

confidence: 99%

Impact of Screens Around Bearings on the Flow and Heat Transfer in the Vent and Scavenge Oil Pipes in Bearing Chambers

Flouros

Cottier

2010

Journal of Engineering for Gas Turbines and Power

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The aim of this paper is to investigate, first, the effects of screens introduced around bearings and, second, the use of protruded instead of fiush in.stalled vent pipes. The investigation focuses on the air and oil flow distributions and on the heat transfer in the scavenge and the vent pipes in an aeroengine bearing chamber The flow distribution lias an impact on the pipe's wall temperature distribution with the likelihood of generating hot .spots. High tempetatures may cause substantial effects on the health of the lubrication system. Problems may range from oil quality degradation to oil self ignition. A steady state CFD analysis of the heat transfer involving the two-phase air and oil fiow in these pipes is performed using the ANSYS CFX package. It was demon.itrated that whereas .screens around bearings reduce the parasitic los.ses atid vent protrusion reduces the oil fiow to the air/oil separator, however, due to the oil fiow distribution the thetmal effects may lead to high material temperatures and to malfunctions in the engine's lube .sy.'item.

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“…The XCAV term, Eq. [7], reintroduces the shaft speed, N, in the denominator, effectively making Harris and Kotzalas's (13) drag loss term a second-order function of speed.…”

Section: Discussionmentioning

confidence: 99%

“…; and Flouros (5)- (7) for large bore bearings operating under high-speed conditions for gas turbine engines.…”

Section: Introductionmentioning

confidence: 99%

Parametric Testing and Heat Generation Modeling of 133-mm Bore Ball Bearings: Part I—Results with Metal Rolling Elements

Forster¹,

Svendsen²,

Givan³

et al. 2011

Tribology Transactions

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Wright Patterson AFB OH 45433133 mm bore ball bearings with metal rolling elements were tested at the following conditions: speeds from 1.5 × 10 6 to 2.6 × 10 6 DN; thrust loads from 13,350 to 53,400 N; oil delivery temperatures from 66 to 121 • C; and oil flow rates from 7.3 to 11.4 L/min. The resulting bearing outer race temperature, oil exit temperature, and power loss determined from the shaft torque and power loss determined from the oil temperature rise are reported. Experimental power loss values are compared to the analytical results obtained with the computer code SHABERTH.The experimental data are also fitted to an empirical equation to predict the total bearing power loss. The results indicate that bearing operating temperature is a challenge for next-generation engines, primarily driven by limits of polyolester lubricants used in gas turbine engines. The results also indicate that the computer code SHABERTH underpredicts the bearing lower loss at high load conditions. A new empirical model was able to reasonably predict the bearing power loss over the conditions studied.

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Reduction of Power Losses in Bearing Chambers Using Porous Screens Surrounding a Ball Bearing

Cited by 13 publications

References 3 publications

CFD Modeling and LDA Measurements for the Air-Flow in an Aero Engine Front Bearing Chamber

CFD Modeling and LDA Measurements for the Air-Flow in an Aero Engine Front Bearing Chamber

Impact of Screens Around Bearings on the Flow and Heat Transfer in the Vent and Scavenge Oil Pipes in Bearing Chambers

Parametric Testing and Heat Generation Modeling of 133-mm Bore Ball Bearings: Part I—Results with Metal Rolling Elements

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