https://cyberleninka.org/article/n/544115.pdf

Hydrodynamic lubrication of textured surfaces: A review of modeling techniques and key findings

A review of vibration-based techniques for helicopter transmission diagnostics

https://hal.archives-ouvertes.fr/hal-01802145/document

Modeling and simulation in tribology across scales: An overview

Using multi-sensor data fusion for vibration fault diagnosis of rolling element bearings by accelerometer and load cell

Clearance control is of paramount importance to turbomachinery designers and is required to meet today's aggressive power output, efficiency, and operational life goals. Excessive clearances lead to losses in cycle efficiency, flow instabilities, and hot gas ingestion into disk cavities. Insufficient clearances limit coolant flows and cause interface rubbing, overheating downstream components and damaging interfaces, thus limiting component life. Designers have put renewed attention on clearance control, as it is often the most cost effective method to enhance system performance. Advanced concepts and proper material selection continue to play important roles in maintaining interface clearances to enable the system to meet design goals. This work presents an overview of turbomachinery sealing to control clearances. Areas covered include: characteristics of gas and steam turbine sealing applications and environments, benefits of sealing, types of standard static and dynamics seals, advanced seal designs, as well as life and limitations issues.

Sealing in Turbomachinery

Even though the list of references associated with this review is rather extensive, in no way does it exhaust the vast literature dedicated to the study of cavitation. The intent was to summarize (i) advances in analytical and numerical modelling, (ii) draw attention to the thermodynamic aspects of cavitation, and (iii) do so while reflecting on physical or experimental observations.

Cavitation formation and modelling for fluid film bearings: A review

This paper describes the experimental pressure and temperature results obtained when rotating a shaft in an eccentric lucite casing at velocities raging from 209 to 628 rad/s (2000 to 6000 rpm). The results are presented in terms of three-dimensional plots and contour maps. Photographic evidence is presented to illustrate how the downstream and upstream regions of the cavity develop and evolve into the well-known finger patterns. A comparison between pressure and temperature profiles in air-saturated oil and carbon dioxide-saturated oil is presented; the origin and nature of the gases contained in the cavity are discussed. Three analytical models (Swift-Stieber, separation, Floberg) predicting the formation of the cavitation zone are presented and evaluated in light of the experimental results. A motion-picture supplement depicting these results is available upon request. Presented as an American Society of Lubrication Engineers paper at the ASME/ASLE Lubrication Conference in Washington, D.C., October 5–...

https://ntrs.nasa.gov/api/citations/19830009562/downloads/19830009562.pdf

An experimental investigation of the vaporous/gaseous cavity characteristics of an eccentric journal bearing

A numerical model based on a transformed, conservative form of the three dimensional Navier-Stokes equation and an analytical model based on lumped fluid parameters are presented and compared with studies of modeled rotor bearing seal systems. The rotor destabilizing factors are related to the rotative character of the flow field. It is shown that these destabilizing factors can be reduced through a decrease in the fluid average circumferential velocity. However, the rotative character of the flow field is a complex three dimensional system with bifurcated secondary flow patterns that significantly alter the fluid circumferential velocity. By transforming the Navier-Stokes equations to those for a rotating observer and using the numerical code PHOENICS-84 with a nonorthogonal body fitted grid, several numerical experiments were carried out to demonstrate the character of this complex flow field. In general, fluid injection and/or preswirl of the flow field opposing the shaft rotation significantly intensified these secondary recirculation zones and thus reduced the average circumferential velocity; injection or preswirl in the direction of rotation significantly weakened these zones.

/pdf/numerical-and-analytical-study-of-fluid-dynamic-forces-in-2ktsza9mur.pdf

Numerical and Analytical Study of Fluid Dynamic Forces in Seals and Bearings

Fibers can be readily fabricated into a variety of seal configurations that are compliant and responsive to high speed or lightly loaded systems. A linear, circular, or contoured brush seal system is a contact seal consisting of the bristle pattern and hardened interface. When compared to a labyrinth seal, the brush seal system is superior and features low leakage, dynamic stability, and permits compliant structures. But in turn, the system usually requires a hardened smooth interface and permits only limited pressure drops. Wear life and wear debris for operations with static or dynamic excitation are largely undetermined. A seal system involves control of fluid within specific boundaries. The brush and rub ring (or rub surface) form a seal system. Design similitudes, a bulk flow model, and rub ring (interface) coatings are discussed. The bulk flow model calculations are based on flows in porous media and filters. The coatings work is based on experience and expanded to include current practice.

/pdf/a-bulk-flow-model-of-a-brush-seal-system-22vd1r94us.pdf

A Bulk Flow Model of a Brush Seal System

This study developed an active tilting-pad journal bearing with a feedback control system to regulate the orbit of a rotating shaft. The control is implemented by means of linear actuators installe...

M. J. Braun

Papers

Cavitation formation and modelling for fluid film bearings: A review

An experimental investigation of the vaporous/gaseous cavity characteristics of an eccentric journal bearing

Numerical and Analytical Study of Fluid Dynamic Forces in Seals and Bearings

A Bulk Flow Model of a Brush Seal System

Simulation and Control of an Active Tilting-Pad Journal Bearing