scholarly journals Measuring Transient High Temperature Thermal Phenomena In Hostile Environment(a)

1980 ◽  
Author(s):  
Byron B. Brenden ◽  
John S. Hartman ◽  
Frederich R. Reich
Keyword(s):  
High Temperature ◽  
Hostile Environment ◽  
Thermal Phenomena

scholarly journals Magneto-thermal phenomena in bulk high temperature superconductors subjected to applied AC magnetic fields

2010 ◽  
Vol 23 (7) ◽  
pp. 075006 ◽  
Author(s):  
P Vanderbemden ◽  
P Laurent ◽  
J-F Fagnard ◽  
M Ausloos ◽  
N Hari Babu ◽  
...  
Keyword(s):  
High Temperature ◽  
Magnetic Fields ◽  
High Temperature Superconductors ◽  
Thermal Phenomena

Loss of frequency response along sampling tubes for the measurements of gaseous composition at high temperature and pressures

1989 ◽  
Vol 208 ◽  
pp. 25-43 ◽  
Author(s):  
Ronald Smith
Keyword(s):  
High Temperature ◽  
Frequency Response ◽  
Steady Flow ◽  
Hostile Environment ◽  
Flow Properties ◽  
Monitoring Equipment ◽  
Low Speed ◽  
Gaseous Composition ◽  
Temporal Variance

Measurements of the rapidly changing gaseous composition in engines at low speed can be made via narrow tubes which convey the gases to monitoring equipment in a less hostile environment. This paper quantifies the extent to which the tube smooths out any changes in concentration. Exact (and approximate) formulae are derived for the temporal variance as weighted double (and single) integrals of the steady flow properties along the tube. Such is the non-uniformity that typically the region near the engine contributes 100 times as much to the spreading as does the region near the monitoring equipment. The advantages of keeping the sampling tubes short and heated are made explicit.

Performance of Powder-Lubricated Journal Bearings With MoS2 Powder: Experimental Study of Thermal Phenomena

1995 ◽  
Vol 117 (3) ◽  
pp. 506-512 ◽  
Author(s):  
H. Heshmat ◽  
D. Brewe
Keyword(s):  
Friction Coefficient ◽  
Outer Space ◽  
Journal Bearings ◽  
Performance Criteria ◽  
Space Systems ◽  
Hostile Environment ◽  
Lubricant Films ◽  
Powder Flow Rate ◽  
Powder Lubrication ◽  
Thermal Phenomena

Powder-lubricated, quasi-hydrodynamic journal bearings assist in controlling wear and hold promise for integration in outer space systems/mechanisms and in other hostile-environment applications where the use of conventional lubricants is impractical. Described herein are the thermal phenomena and an assessment of the thermal stability, heat generation and dissipation characteristics of slider-type, powder-lubricated bearings. Powder lubricant films provide lift and separate bearing surfaces and cause side leakage. The reduction in friction coefficient and, consequently, in the heat generated in the bearings, drastically reduces wear of the tribomaterials. Further, bearing side leakage carries away most of the heat generated by shear, reducing the heat to the critical bearing surfaces. Also presented are the thermohydrodynamic effects of powder lubrication (MoS2) on bearing performance criteria, e.g., temperature and friction coefficient as a function of speed and load, including the effect of powder flow rate on bearing performance and wear.

Small Modular Reactor Thermal Performance Improvement With Addition of a High Temperature Gas Reactor Superheater

2014 ◽  
Author(s):  
Paul J. Marotta ◽  
Basil N. Antar
Keyword(s):  
Heat Flux ◽  
High Temperature ◽  
Power Output ◽  
Thermal Source ◽  
Steam Quality ◽  
Two Phase ◽  
Small Modular Reactor ◽  
Axial Heat ◽  
Thermal Phenomena ◽  
High Temperature Gas

Reheating steam from a Small Modular Reactor (SMR) is explored in order to increase efficiency and power output. A thermal source in the form of a High Temperature Gas Reactor (HTGR) is considered. Engineering challenges include proof-of-principle, reactor sizing, evaluation, and feasibility. The proposed thermodynamic process modifications have been evaluated for a range of inlet steam quality conditions. The evaluation of the steam tube dimensions and number of optimal tubes have been calculated utilizing the so-called Log Mean Temperature Difference method. Subsequently, the performance of the steam tubes was further analyzed within a RELAP5 model to investigate two phase boiling flow thermal phenomena. Detailed calculations include a non-uniform axial heat flux distribution based on published results for the tri-structural isotropic fuel system (TRISO). Non-uniform axial heat flux served as the non-uniform heat source boundary condition in the computer model for the High Temperature Gas Reactor. The work shows that the proposed modifications are not only feasible but also show significant improvement for power output in the amount of over 50%, and increase of the power cycle efficiency of over 14%.

Influence of Thermo-Mechanical Processing on the Microstructure of Beryllia Dispersed Nickel Alloys

1973 ◽  
Vol 31 ◽  
pp. 184-185
Author(s):  
M.S. Grewal ◽  
S.A. Sastri ◽  
N.J. Grant
Keyword(s):  
High Temperature ◽  
Nickel Alloys ◽  
Thermomechanical Processing ◽  
Cold Work ◽  
High Temperature Strength ◽  
Strengthening Effect ◽  
Mechanical Processing ◽  
Uniform Dispersion ◽  
Oxide Particles ◽  
Nickel Base

Currently there is a great interest in developing nickel base alloys with fine and uniform dispersion of stable oxide particles, for high temperature applications. It is well known that the high temperature strength and stability of an oxide dispersed alloy can be greatly improved by appropriate thermomechanical processing, but the mechanism of this strengthening effect is not well understood. This investigation was undertaken to study the dislocation substructures formed in beryllia dispersed nickel alloys as a function of cold work both with and without intermediate anneals. Two alloys, one Ni-lv/oBeo and other Ni-4.5Mo-30Co-2v/oBeo were investigated. The influence of the substructures produced by Thermo-Mechanical Processing (TMP) on the high temperature creep properties of these alloys was also evaluated.

Application of TEM to Deformation, Wear, and Fracture of Ceramics

1974 ◽  
Vol 32 ◽  
pp. 472-473
Author(s):  
B. J. Hockey
Keyword(s):  
Wear Resistance ◽  
High Temperature ◽  
Mechanical Behavior ◽  
Brittle Materials ◽  
High Temperature Strength ◽  
Wide Range ◽  
Corrosive Environments ◽  
Further Development

Ceramics, such as Al2O3 and SiC have numerous current and potential uses in applications where high temperature strength, hardness, and wear resistance are required often in corrosive environments. These materials are, however, highly anisotropic and brittle, so that their mechanical behavior is often unpredictable. The further development of these materials will require a better understanding of the basic mechanisms controlling deformation, wear, and fracture.The purpose of this talk is to describe applications of TEM to the study of the deformation, wear, and fracture of Al2O3. Similar studies are currently being conducted on SiC and the techniques involved should be applicable to a wide range of hard, brittle materials.

Lattice Imaging of Grain Boundaries in Ceramics

1977 ◽  
Vol 35 ◽  
pp. 114-115
Author(s):  
D. R. Clarke ◽  
G. Thomas
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Grain Boundaries ◽  
High Temperature Strength ◽  
Current Interest ◽  
Lattice Imaging ◽  
Special Significance ◽  
Structural Applications ◽  
Refractory Ceramics

Grain boundaries have long held a special significance to ceramicists. In part, this has been because it has been impossible until now to actually observe the boundaries themselves. Just as important, however, is the fact that the grain boundaries and their environs have a determing influence on both the mechanisms by which powder compaction occurs during fabrication, and on the overall mechanical properties of the material. One area where the grain boundary plays a particularly important role is in the high temperature strength of hot-pressed ceramics. This is a subject of current interest as extensive efforts are being made to develop ceramics, such as silicon nitride alloys, for high temperature structural applications. In this presentation we describe how the techniques of lattice fringe imaging have made it possible to study the grain boundaries in a number of refractory ceramics, and illustrate some of the findings.

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