Improved infrared temperature mapping of elastohydrodynamic contacts

2009 ◽  
Vol 223 (8) ◽  
pp. 1165-1177 ◽  
Author(s):  
T Reddyhoff ◽  
H A Spikes ◽  
A V Olver
Keyword(s):  
Effective Means ◽  
Field Measurements ◽  
Operating Conditions ◽  
Mapping Technique ◽  
Shear Stresses ◽  
Measured Temperature ◽  
Ir Camera ◽  
Full Field ◽  
Group I ◽  
Increased Sensitivity

An effective means of studying lubricant rheology within elastohydrodynamic contacts is by detailed mapping of the temperature of the fluid and the bounding surfaces within the lubricated contact area. In the current work, the experimental approach initially developed by Sanborn and Winer and then by Spikes et al., has been advanced to include a high specification infrared (IR) camera and microscope. Besides the instantaneous capture of full field measurements, this has the advantage of increased sensitivity and higher spatial resolution than previous systems used. The increased sensitivity enables a much larger range of testable operating conditions: namely lower loads, speeds, and reduced sliding. In addition, the range of test lubricants can be extended beyond high shearing traction fluids. These new possibilities have been used to investigate and compare the rheological properties of a range of lubricants: namely a group I and group II mineral oil, a polyalphaolephin (group IV), the traction fluid Santotrac 50, and 5P4E, a five-ring polyphenyl-ether. As expected, contact temperatures increased with lubricant refinement, for the mineral base oils tested. Using moving heat source theory, the measured temperature distributions were converted into maps showing rate of heat input into each surface, from which shear stresses were calculated. The technique could therefore be validated by integrating these shear stress maps, and comparing them with traction values obtained by direct measurement. Generally there was good agreement between the two approaches, with the only significant differences occurring for 5P4E, where the traction that was deduced from the temperature over-predicted the traction by roughly 15 per cent. Of the lubricants tested, Santotrac 50 showed the highest average traction over the contact; however, 5P4E showed the highest maximum traction. This observation is only possible using the IR mapping technique, and is obscured when measuring the traction directly. Both techniques showed the effect of shear heating causing a reduction in traction.

Improved Temperature Mapping of EHL Contacts

2008 ◽  
Author(s):  
T. Reddyhoff ◽  
H. A. Spikes ◽  
A. V. Olver
Keyword(s):  
Effective Means ◽  
Field Measurements ◽  
Operating Conditions ◽  
Additional Advantage ◽  
Ir Camera ◽  
Full Field ◽  
Traction Fluid ◽  
Increased Sensitivity ◽  
Cooling Effects ◽  
Traction Fluids

An effective means of studying lubricant film rheology within EHL contacts is by detailed mapping of the temperature of the fluid and the bounding surfaces within the lubricated contact area. This provides a way of directly measuring the rheology of lubricant films under true EHL conditions. Furthermore, temperature measurement itself provides a very effective means of testing and validating computer simulations. In the current work, the experimental approach initially developed by Sanborn and Winer [1] and then by Spikes and co-workers [2], has been advanced to include a high specification infrared (IR) camera and microscope. This is a similar approach to that taken by Yagi and Kyogoku [3]. As well as the instantaneous capture of full field measurements, this has the advantage of increased sensitivity and higher spatial resolution than previous systems used. The increased sensitivity enables a much larger range of testable operating conditions; namely lower loads, speeds and reduced sliding. In addition, the range of test lubricants can be extended beyond high shearing traction fluids. One additional advantage of instantaneous full field measurements is that the weak infrared optical interference caused by the film can be observed and can used to exactly locate the centre of the contact in the resulting temperature maps. These new possibilities have been used to investigate and compare the rheological properties and compression cooling effects exhibited by a PAO, a group II mineral oil, and a traction fluid.

Development of Non-Destructive Heat Resistance Evaluation System for TBC on Gas Turbine Blade

2010 ◽  
Author(s):  
Tomoharu Fujii ◽  
Toshihiko Takahashi ◽  
Eiji Sakai ◽  
Terutaka Fujioka
Keyword(s):  
Heat Resistance ◽  
Gas Turbine ◽  
Evaluation System ◽  
Carbon Dioxide Laser ◽  
High Efficiency ◽  
Operating Conditions ◽  
Residual Lifetime ◽  
Cylindrical Shape ◽  
Measured Temperature ◽  
Ir Camera

The use of thermal barrier coatings (TBCs) is the key technique for realizing high-efficiency gas turbine combined cycles. Hence, TBCs are applied to various hot gas path components such as combustors, blades, and vanes. The application of a TBC causes a significant decrease in the temperature of the base metal surface. Consequently, the lifetime of the component is increased. However, it is reported that under high-temperature operating conditions, the heat resistance of the TBC decreases gradually because of sintering and erosion of the TBC layer. Accurate evaluation of changes in the TBC heat resistance is very important for evaluating the residual lifetime of a given component. We have previously developed a nondestructive technique for measuring the heat resistance of TBCs applied on the inner surface of a combustion liner. In this technique, the TBC surface is heated by a laser beam, and the temperature change of this heated point is measured by an IR camera. The heat resistance is calculated from the measured temperature. On the basis of this concept, we have made improvements to this technique so that it can be used to measure the heat resistance of a TBC layer on a blade surface. However, several difficulties are encountered when using this technique for the abovementioned purpose. For example, the blade has a three-dimensional (3D) surface and complex internal cooling paths, as opposed to the combustion liner, which has a simple cylindrical shape. Hence, it is difficult to keep the same heating condition at any surface. To overcome these difficulties, we propose a new concept and develop a system for measuring the heat resistance of the TBC layer on a blade. This system is mainly composed of a carbon dioxide laser, a robot arm, and an IR camera. In this paper, we present an overview of the developed system.

scholarly journals Stereo-DIC Measurements of a Vibrating Bladed Disk: In-Depth Analysis of Full-Field Deformed Shapes

2021 ◽  
Vol 11 (12) ◽  
pp. 5430
Author(s):  
Paolo Neri ◽  
Alessandro Paoli ◽  
Ciro Santus
Keyword(s):  
Single Point ◽  
Excitation Frequency ◽  
Phase Variation ◽  
Operating Conditions ◽  
Image Correlation ◽  
Response Analysis ◽  
Full Field ◽  
Low Speed ◽  
Bladed Disk ◽  
Depth Analysis

Vibration measurements of turbomachinery components are of utmost importance to characterize the dynamic behavior of rotating machines, thus preventing undesired operating conditions. Local techniques such as strain gauges or laser Doppler vibrometers are usually adopted to collect vibration data. However, these approaches provide single-point and generally 1D measurements. The present work proposes an optical technique, which uses two low-speed cameras, a multimedia projector, and three-dimensional digital image correlation (3D-DIC) to provide full-field measurements of a bladed disk undergoing harmonic response analysis (i.e., pure sinusoidal excitation) in the kHz range. The proposed approach exploits a downsampling strategy to overcome the limitations introduced by low-speed cameras. The developed experimental setup was used to measure the response of a bladed disk subjected to an excitation frequency above 6 kHz, providing a deep insight in the deformed shapes, in terms of amplitude and phase distributions, which could not be feasible with single-point sensors. Results demonstrated the system’s effectiveness in measuring amplitudes of few microns, also evidencing blade mistuning effects. A deeper insight into the deformed shape analysis was provided by considering the phase maps on the entire blisk geometry, and phase variation lines were observed on the blades for high excitation frequency.

Field evidence of resuspension in a mine tailings pond

2001 ◽  
Vol 38 (4) ◽  
pp. 796-808 ◽  
Author(s):  
Celestina Adu-Wusu ◽  
Ernest K Yanful ◽  
Mohammed H Mian
Keyword(s):  
Shear Stress ◽  
Mine Tailings ◽  
Critical Shear Stress ◽  
Field Measurements ◽  
Shear Stresses ◽  
Wind Speeds ◽  
Tailings Pond ◽  
Field Evidence ◽  
Water Cover ◽  
Solubility Of Oxygen

Flooding of tailings under shallow water covers is an effective method of decommissioning potentially acid generating mine tailings. The low diffusivity and solubility of oxygen in water are attractive features of this technology. However, wind-induced waves can resuspend flooded tailings and expose them to greater contact with dissolved oxygen, thereby increasing the potential for oxidation and acid generation. Field measurements of wind activity and waves under different water cover depths and associated resuspension for a mine tailings pond in Ontario are presented and discussed. The results show that wind speeds greater than 8 m/s above water covers that are shallower than 1 m create waves of height greater than 10 cm and bottom shear stresses greater than 0.2 Pa. Under these conditions the critical shear stress of the mine tailings was exceeded, resulting in erosion and subsequent resuspension.Key words: mine tailings, water cover, wind-induced waves, resuspension, wind speed, shear stress.

In-situ Full Field Measurements During Inter-Facial Debonding in Single Fiber Composite Under Transverse Load

2018 ◽  
Vol 58 (9) ◽  
pp. 1451-1467 ◽  
Author(s):  
I. Tabiai ◽  
R. Delorme ◽  
D. Therriault ◽  
M. Levesque
Keyword(s):  
Fiber Composite ◽  
Field Measurements ◽  
Single Fiber ◽  
Transverse Load ◽  
Full Field

Sedimentation in Storage Tank Structures

1994 ◽  
Vol 29 (1-2) ◽  
pp. 363-372 ◽  
Author(s):  
Virginia R. Stovin ◽  
Adrian J. Saul
Keyword(s):  
Numerical Models ◽  
Effective Means ◽  
Design Guidelines ◽  
Laboratory Model ◽  
Shear Stresses ◽  
Model Situation ◽  
Combined Sewer ◽  
Urban Watercourse ◽  
Storage Structures ◽  
Selection Of

Although storage tanks provide an effective means of reducing the magnitude and frequency of combined sewer overflow discharges, and thereby of alleviating urban watercourse pollution, poorly designed storage structures frequently suffer from maintenance problems arising from sedimentation. The development of design guidelines that optimise the self-cleansing operation of storage structures is clearly a priority for urban drainage research. This paper describes a system that has been developed to study sediment deposition in laboratory model-scale storage structures. The patterns of deposition resulting from a selection of flow regimes are described, and the need for time-varying and time series storm tests is highlighted. Sedimentation patterns are shown to predominantly depend on the flow field, and the critical bed shear stresses for deposition and erosion in the model situation are identified. Hence, the potential application of numerical models to the design problem is discussed.

Incorporating Neural Network Material Models Within Finite Element Analysis for Rheological Behavior Prediction

2006 ◽  
Vol 129 (1) ◽  
pp. 58-65 ◽  
Author(s):  
B. Scott Kessler ◽  
A. Sherif El-Gizawy ◽  
Douglas E. Smith
Keyword(s):  
Finite Element ◽  
Effective Means ◽  
Element Model ◽  
Operating Conditions ◽  
Behavior Prediction ◽  
Element Analysis ◽  
Material Models ◽  
Rheological Models ◽  
Wide Range ◽  
Novel Method

The accuracy of a finite element model for design and analysis of a metal forging operation is limited by the incorporated material model’s ability to predict deformation behavior over a wide range of operating conditions. Current rheological models prove deficient in several respects due to the difficulty in establishing complicated relations between many parameters. More recently, artificial neural networks (ANN) have been suggested as an effective means to overcome these difficulties. To this end, a robust ANN with the ability to determine flow stresses based on strain, strain rate, and temperature is developed and linked with finite element code. Comparisons of this novel method with conventional means are carried out to demonstrate the advantages of this approach.

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