Capacitive Film Thickness Measurements in a Ventless Aero-Engine Bearing Chamber—Influence of Operating Conditions and Offtake Design

2013 ◽  
Vol 135 (11) ◽  
Author(s):  
Wolfram Kurz ◽  
Klaus Dullenkopf ◽  
Hans-Jörg Bauer
Keyword(s):  
Film Thickness ◽  
Thickness Distribution ◽  
Operating Conditions ◽  
Chamber Pressure ◽  
Shaft Speed ◽  
Suitable Parameter ◽  
Accuracy And Repeatability ◽  
Thickness Measurements ◽  
Engine Bearing

The paper presents results from film thickness measurements in a bearing chamber test rig. The measurements were performed at different operating conditions and with two offtake designs. A discussion of the measurement technique using in situ calibrated capacitive sensors shows good accuracy and repeatability. The film thickness results are first compared to measurements with the same chamber in a vented configuration. The analysis of the measurements at various operating conditions shows a strong influence of the shaft speed, the chamber pressure, and the offtake design. In contrast to that, flow rate and scavenge ratio have only minor influence. Furthermore, the momentum flux of the core air flow is proposed as a suitable parameter with which the influence of shaft speed and pressure can be correlated to the film thickness distribution.

Capacitive Film Thickness Measurements in a Ventless Aero-Engine Bearing Chamber: Influence of Operating Conditions and Offtake Design

2013 ◽  
Author(s):  
Wolfram Kurz ◽  
Klaus Dullenkopf ◽  
Hans-Jörg Bauer
Keyword(s):  
Film Thickness ◽  
Thickness Distribution ◽  
Operating Conditions ◽  
Chamber Pressure ◽  
Shaft Speed ◽  
Suitable Parameter ◽  
Accuracy And Repeatability ◽  
Thickness Measurements ◽  
Engine Bearing

The paper presents results from film thickness measurements in a bearing chamber test rig. The measurements were performed at different operating conditions and with two offtake designs. A discussion of the measurement technique using in-situ calibrated capacitive sensors shows good accuracy and repeatability. The film thickness results are first compared to measurements with the same chamber in a vented configuration. The analysis of the measurements at various operating conditions shows a strong influence of the shaft speed, the chamber pressure, and the offtake design. In contrast to that, flow rate and scavenge ratio have only minor influence. Furthermore, the momentum flux of the core air flow is proposed as a suitable parameter with which the influence of shaft speed and pressure can be correlated to the film thickness distribution.

scholarly journals Measuring and inferring the ice thickness distribution of four glaciers in the Tien Shan, Kyrgyzstan

2020 ◽  
pp. 1-18
Author(s):  
Lander Van Tricht ◽  
Philippe Huybrechts ◽  
Jonas Van Breedam ◽  
Johannes J. Fürst ◽  
Oleg Rybak ◽  
...  
Keyword(s):  
Cross Validation ◽  
Thickness Distribution ◽  
Tien Shan ◽  
Ice Thickness ◽  
Ice Volume ◽  
In Situ Data ◽  
Radio Echo Sounding ◽  
Thickness Measurements ◽  
Tien Shan Mountains

Abstract Glaciers in the Tien Shan mountains contribute considerably to the fresh water used for irrigation, households and energy supply in the dry lowland areas of Kyrgyzstan and its neighbouring countries. To date, reconstructions of the current ice volume and ice thickness distribution remain scarce, and accurate data are largely lacking at the local scale. Here, we present a detailed ice thickness distribution of Ashu-Tor, Bordu, Golubin and Kara-Batkak glaciers derived from radio-echo sounding measurements and modelling. All the ice thickness measurements are used to calibrate three individual models to estimate the ice thickness in inaccessible areas. A cross-validation between modelled and measured ice thickness for a subset of the data is performed to attribute a weight to every model and to assemble a final composite ice thickness distribution for every glacier. Results reveal the thickest ice on Ashu-Tor glacier with values up to 201 ± 12 m. The ice thickness measurements and distributions are also compared with estimates composed without the use of in situ data. These estimates approach the total ice volume well, but local ice thicknesses vary substantially.

An Accurate Solution of the Gas Lubricated, Flat Sector Thrust Bearing

1977 ◽  
Vol 99 (1) ◽  
pp. 82-88 ◽  
Author(s):  
I. Etsion ◽  
D. P. Fleming
Keyword(s):  
Film Thickness ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Thickness Distribution ◽  
Maximum Load ◽  
Accurate Solution ◽  
Operating Conditions ◽  
Thrust Bearings ◽  
Practical Design ◽  
Minimum Film Thickness

A flat sector shaped pad geometry for gas lubricated thrust bearings is analyzed considering both pitch and roll angles of the pad and the true film thickness distribution. Maximum load capacity is achieved when the pad is tilted so as to create a uniform minimum film thickness along the pad trailing edge. Performance characteristics for various geometries and operating conditions of gas thrust bearings are presented in the form of design curves. A comparison is made with the rectangular slider approximation. It is found that this approximation is unsafe for practical design, since it always overestimates load capacity.

Steady State Performance Characteristics of a Tilting Pad Thrust Bearing

2000 ◽  
Vol 123 (3) ◽  
pp. 608-615 ◽  
Author(s):  
Sergei B. Glavatskikh
Keyword(s):  
Steady State ◽  
Film Thickness ◽  
Thrust Bearing ◽  
Operating Conditions ◽  
Performance Characteristics ◽  
Shaft Speed ◽  
Oil Film ◽  
Tilting Pad ◽  
Bearing Load ◽  
Steady State Performance

The paper reports results of the experimental investigation into the steady state performance characteristics of a tilting pad thrust bearing typical of design in general use. Simultaneous measurements are taken of the pad and collar temperatures, the pressure distributions, oil film thickness, and power loss as a function of shaft speed, bearing load, and supplied oil temperature. The effect of operating conditions on bearing performance is discussed. A small radial temperature variation is observed in the collar. A reduction in minimum oil film thickness with load is approximately proportional to p−0.6, where p is an average bearing pressure. It has also been found that the oil film pressure profiles change not only due to the average bearing load but also with an increase in shaft speed and temperature of the supplied oil.

Elastohydrodynamie Lubrication of Big-End Bearings Part 2: Ratification

1991 ◽  
Vol 205 (2) ◽  
pp. 107-119 ◽  
Author(s):  
M B Aitken ◽  
H McCallion
Keyword(s):  
Film Thickness ◽  
Close Correlation ◽  
Connecting Rod ◽  
Test Rig ◽  
Collapse Mechanisms ◽  
Minimum Film Thickness ◽  
Inertial Loading ◽  
Film Collapse ◽  
Thickness Measurements

The elastohydrodynamic analysis developed in Part 1 of this work is ratified against previous Ruston and Hornsby big-end studies. Sufficiently close correlation with published in situ film-thickness measurements allows big-end bearing performance to be determined with some confidence; significant new insight was obtained. Elasticity body forces from connecting-rod motion were found to be an integral component of the big-end representation; it is a prevalent misconception that these forces can be neglected from theoretical as well as experimental test-rig works. Film collapse mechanisms, likened to vapour cavitation, were observed in the dynamically loaded elastic bearing; these were not detected in equivalent rigid bearing simulations. Cyclic minimum film thickness was observed during inertial loading, irrespective of gas force loading. Two separate minimum-film conditions were identified: one in the connecting-rod's neck and a second, at higher load, in the rod's cap. The second condition is critical from a design standpoint; significantly thinner films are predicted than by rigid bearing theory.

Planarization Ability of Chemical Mechanical Planarization (Cmp) Processes

1994 ◽  
Vol 337 ◽  
Author(s):  
Matt Stell ◽  
Rahul Jairath ◽  
Mukesh Desai ◽  
Robert Tolles
Keyword(s):  
Film Thickness ◽  
Chemical Mechanical Planarization ◽  
Silica Particles ◽  
The Other ◽  
Ph Values ◽  
Enhanced Solubility ◽  
Experimental Approaches ◽  
Thickness Measurements

ABSTRACTMethods for determining planarization ability of CMP were explored. Options included film thickness measurements of the dielectric over metal and field, TIR measurements using profilometry, and a combination of the two. The attempt to observe the in situ change in the topography was addressed in two distinct experimental approaches. The first approach involved processing wafers for predetermined intervals. The other approach processed different wafers for different amounts of time. The effects of down force and platen rpm on planarization ability were studied using the first approach. Results indicate that planarization is more efficient at higher down forces and higher platen rpm. Slurry property effects were examined using the second method. The planarization ability appears to suffer at elevated pH values. This is attributed to both the enhanced solubility of the silica particles and the dielectric itself.

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.

scholarly journals Starved Lubrication of Elliptical EHD Contacts

2004 ◽  
Vol 126 (1) ◽  
pp. 105-111 ◽  
Author(s):  
B. Damiens ◽  
C. H. Venner ◽  
P. M. E. Cann ◽  
A. A. Lubrecht
Keyword(s):  
Numerical Model ◽  
Film Thickness ◽  
Numerical Simulations ◽  
Excellent Agreement ◽  
Experimental Approach ◽  
Operating Conditions ◽  
Inlet Region ◽  
Inlet Length ◽  
Thickness Measurements ◽  
Circular Contact

This paper focuses on the lubrication behavior of starved elliptical Elasto-HydroDynamic (EHD) contacts. Starvation is governed by the amount of lubricant available in the inlet region and can result in much thinner films than occurring under fully flooded conditions. Therefore, it would be desirable to be able to predict the onset and severity of starvation and to be able to relate film reduction directly to the operating conditions and lubricant properties. The aim of this work is to explore the influence of these parameters on starvation. A combined modeling and experimental approach has been employed. The numerical model has been developed from an earlier circular contact study [1]. In this model, the amount and distribution of the lubricant in the inlet region determines the onset of starvation and predicts the film decay in the contact. Numerical simulations for a uniform layer on the surface show that a single parameter, characteristic of the inlet length of the contact in the fully flooded regime, determines the starved behavior. Film thickness measurements under starved conditions were performed to validate this theory. For a circular contact excellent agreement was found. In theory the same mechanism applies to elliptic contacts, however, the behavior is more complicated.

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