Influences on the Oil Split Between the Offtakes of an Aero-Engine Bearing Chamber

2012 ◽  
Author(s):  
Wolfram Kurz ◽  
Klaus Dullenkopf ◽  
Hans-Jörg Bauer
Keyword(s):  
Film Thickness ◽  
Test Rig ◽  
Oil Film ◽  
Aero Engine ◽  
The Impact ◽  
Engine Bearing

The aim of the presented work was to identify factors that influence the oil split between the two offtakes of a vented aero-engine bearing chamber. The impact of different vent and scavenge offtake designs was experimentally investigated with a test rig at the ITS. The generic bearing chamber was also equipped with ten film thickness sensors. The film measurements allowed a further evaluation of the mechanisms behind different oil splits. Two of the examined offtake features ensured a very constant oil split: a protruding vent and a covered ramp offtake. The latter also decreased the oil film thickness on the bearing chamber walls significantly. Furthermore, an influence of a non-uniform seal gap was detected which altered the oil split by several percent.

A Numerical Model for Oil Film Flow in an Aero-Engine Bearing Chamber and Comparison With Experimental Data

2004 ◽  
Author(s):  
Mark Farrall ◽  
Kathy Simmons ◽  
Stephen Hibberd ◽  
Philippe Gorse
Keyword(s):  
Experimental Data ◽  
Boundary Conditions ◽  
Roller Bearing ◽  
Numerical Approach ◽  
Oil Droplets ◽  
Two Phase ◽  
Oil Film ◽  
Aero Engine ◽  
The Impact ◽  
Engine Bearing

The work presented forms part of an on-going investigation, focusing on modelling the motion of a wall oil film present in a bearing chamber and comparison with existing experimental data. The film is generated through the impingement of oil droplets shed from a roller bearing. Momentum resulting from the impact of oil droplets, interfacial shear from the airflow, and gravity cause the film to migrate around the chamber. Oil and air exit the chamber at scavenge and vent ports. A previously reported numerical approach to the simulation of steady-state two-phase flow in a bearing chamber, that includes in-house sub-models for droplet-film interaction and oil film motion, has been extended. This paper includes the addition of boundary conditions for the vent and scavenge together with a comparison to experimental results obtained from ITS, University of Karlsruhe. The solution is found to be sensitive to the choice of boundary conditions applied to the vent and scavenge.

An Approach for Predicting the Flow Regime in an Aero Engine Bearing Chamber

2014 ◽  
Author(s):  
Wolfram Kurz ◽  
Hans-Jörg Bauer
Keyword(s):  
Flow Regime ◽  
Air Flow ◽  
Flow Regimes ◽  
Chamber Pressure ◽  
Test Rig ◽  
Oil Viscosity ◽  
Oil Film ◽  
Aero Engine ◽  
Oil Flow ◽  
Engine Bearing

The paper discusses an approach to predict the two-phase flow regime in an aero engine bearing chamber. In general, one of two distinct flow regimes can occur in a bearing chamber. At lower shaft speeds, the oil flow is only partially affected by the air flow, which is driven by the rotating shaft. At higher shaft speeds, however, the rotating air flow forces the oil film at the chamber walls to rotate, too. Thus, the two flow regimes correspond to two very different oil film distributions inside a bearing chamber presumably with significant consequences for the internal wall heat transfer. In order to determine the driving parameters for the flow regimes and the change between them, experiments were carried out with a bearing chamber test rig. With this test rig all relevant operating parameters as well as the geometry of the bearing chamber could be varied independently. The analysis of the experimental data allowed defining a general parameter which takes into account the chamber pressure, shaft speed, oil viscosity and chamber length. The influence of the oil flow rate and the overall dimensions are assessed qualitatively.

scholarly journals Prediction of Film Thickness of an Aero-Engine Bearing Chamber Using Coupled VOF and Thin Film Model

2019 ◽  
Author(s):  
Kuldeep Singh ◽  
Medhat Sharabi ◽  
Stephen Ambrose ◽  
Carol Eastwick ◽  
Richard Jefferson-Loveday
Keyword(s):  
Thin Film ◽  
Film Thickness ◽  
Air Flow ◽  
Shaft Speed ◽  
Oil Film ◽  
Film Model ◽  
Thin Film Model ◽  
Wide Range ◽  
Aero Engine ◽  
Engine Bearing

Abstract In the present work, a coupled volume-of-fluid (VOF) model with Eulerian thin-film model (ETFM) approach is used to predict the film thickness in an aero-engine bearing chamber. Numerical studies are conducted for a wide range of shaft speeds with lubricant and air flow rates of 100 1/hr and 10 g/s respectively, at a scavenge ratio of 4 on a simplified bearing chamber test rig. Air-flow analysis inside the bearing chamber is also assessed. Primary and secondary airflow predictions are found to be in good agreement with the experimental results. The coupled ETFM+VOF approach is found to be sensitive enough to capture the qualitative trend of oil film formation and distribution over the chamber wall. Oil collection near the sump at a low shaft speed and a rotating oil film at a higher shaft speed are well captured.

An adjustable oil film thickness test rig for detecting lubrication characteristics of slipper/swash-pair in piston pumps

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Haiji Wang ◽  
Guanglin Shi
Keyword(s):  
Film Thickness ◽  
Peer Review ◽  
Relative Error ◽  
Mathematical Analysis ◽  
Test Rig ◽  
Content Type ◽  
Oil Film ◽  
Displacement Sensors ◽  
Measuring Machine ◽  
Lubrication Characteristics

Purpose The purpose of this paper is to propose an adjustable oil film thickness test rig for detecting lubrication characteristics of the slipper. The mathematical analysis of lubrication is introduced. Based on the results from the test rig, the results comparison from test rig and mathematical analysis is carried out. Design/methodology/approach This paper introduces a mechanism which can adjust the oil film thickness between the slipper and swash-plate. Feasibility is ensured, and the accuracy of test rig is guaranteed by the three-coordinate measuring machine. Three displacement sensors show the oil film thickness and its shape. The reacting force and torque resulting from oil film can be achieved by three S-type force sensors and a torque sensor, respectively. Findings The relative error of the reacting force is small. The relative error reduces and is acceptable when the deformation of retainer is taken into account. The thickness and tilt angle of oil film have less effect on the reacting force. However, they are significantly impact on torque. Originality/value The test rig proposed in this paper is able to adjust the oil film thickness, which is used to detecting the lubrication characteristics in pump design. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2020-0166/

Influence of High Rotational Speeds on Heat Transfer and Oil Film Thickness in Aero-Engine Bearing Chambers

1994 ◽  
Vol 116 (2) ◽  
pp. 395-401 ◽  
Author(s):  
S. Wittig ◽  
A. Glahn ◽  
J. Himmelsbach
Keyword(s):  
Heat Transfer ◽  
Film Thickness ◽  
Thermal Loading ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Test Facility ◽  
High Rotational Speed ◽  
Oil Film ◽  
Aero Engine

Increasing the thermal loading of bearing chambers in modern aero-engines requires advanced techniques for the determination of heat transfer characteristics. In the present study, film thickness and heat transfer measurements have been carried out for the complex two-phase oil/air flow in bearing chambers. In order to ensure real engine conditions, a new test facility has been built up, designed for rotational speeds up to n = 16,000 rpm and maximum flow temperatures of Tmax = 473 K. Sealing air and lubrication oil flow can be varied nearly in the whole range of aero-engine applications. Special interest is directed toward the development of an ultrasonic oil film thickness measuring technique, which can be used without any reaction on the flow inside the chamber. The determination of local heat transfer at the bearing chamber housing is based on a well-known temperature gradient method using surface temperature measurements and a finite element code to determine temperature distributions within the bearing chamber housing. The influence of high rotational speed on the local heat transfer and the oil film thickness is discussed.

scholarly journals Assessment of an Enhanced Thin Film Model to Capture Wetting and Drying Behavior in an Aero-Engine Bearing Chamber

2019 ◽  
Author(s):  
Kuldeep Singh ◽  
Medhat Sharabi ◽  
Stephen Ambrose ◽  
Carol Eastwick ◽  
Richard Jefferson-Loveday ◽  
...  
Keyword(s):  
Thin Film ◽  
Contact Angle ◽  
Film Thickness ◽  
Wetting And Drying ◽  
Film Model ◽  
Thin Film Model ◽  
Aero Engine ◽  
Thickness Prediction ◽  
Drying Behavior ◽  
Engine Bearing

Abstract In the present work, a wetting and drying model is coupled with Eulerian Thin-Film model (ETFM) to analyze the wetting and drying behavior inside the bearing chamber. In the enhanced model, an additional source term is included to account for the contact angle effect. These models were coupled with volume-of-fluid (VOF) such that the core region is resolved by VOF and region close to the chamber walls, where a thin film is expected is resolved by either ETFM or enhanced ETFM model. Numerical studies are conducted for a shaft speed of 5,000 rpm, lubricant and air flow rates of 100 1/hr and 10 g/s respectively, at a scavenging ratio of 4. In the case of enhanced ETFM model lubricant to surface contact angle was varied from 10° to 45°. The performance of enhanced ETFM model is evaluated to capture drying and wetting behavior on a flat plate and found to be satisfactory. Film thickness prediction of enhanced ETFM model is found to be comparable with the VOF predictions reported in the literature. The effect of contact angle on the spreading of oil and film thickness is found to be small for the investigated conditions on an aero-engine bearing chamber.

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