Thermal Buckling and Snapping of a Circular Ring

1971 ◽  
Vol 93 (4) ◽  
pp. 1245-1254
Author(s):  
David Burgreen
Keyword(s):  
Temperature Distribution ◽  
Temperature Variation ◽  
Circular Ring ◽  
Thermal Buckling ◽  
Uniform Temperature ◽  
Radial Temperature ◽  
Axial Temperature ◽  
Axisymmetric Temperature

An analysis is made of the thermal buckling of flat rings and of shallow conical rings which are subjected to an axisymmetric temperature distribution. It is found that flat rings can buckle when there is a radial temperature variation only. Conical rings are subject to instability and snapping in the presence of either an axial temperature variation alone, or a combined axial and radial temperature variation, of the proper magnitude. Expressions are developed which give the temperatures at which buckling and snapping take place, as well as the temperature over-lap in a full thermostatic cycle of increasing and decreasing temperatures. Bimetallic conical rings at uniform temperature are examined, and snapping temperatures are determined for this type element.

Analysis of Temperature and Heat Flow Characteristics in Underground Tunnel

2014 ◽  
Vol 955-959 ◽  
pp. 4083-4086 ◽  
Author(s):  
Hai Min Xie ◽  
Mao De Li
Keyword(s):  
Numerical Simulation ◽  
Temperature Distribution ◽  
Heat Flow ◽  
Thermal Environment ◽  
Flow Characteristics ◽  
Surrounding Rock ◽  
Simplified Model ◽  
Radial Temperature ◽  
Underground Tunnel ◽  
Axial Temperature

This paper summarizes the two methods which are experimental research and numerical simulation to thermal environment of the tunnel. Then the latest developments of the thermal environment research at home and overseas are introduced. At last a simplified model of thermal environment of underground tunnel is established. Through CFD software, the radial temperature distribution of tunnel surrounding rock and the axial temperature distribution of air at winter and summer conditions are obtained which provide basis for further research on thermal environment.

Impact of Non-Uniform Temperature on Flange Leak Tightness

2013 ◽  
Author(s):  
Gong H. Jung ◽  
Minsu Kim ◽  
Eric Gage
Keyword(s):  
Temperature Distribution ◽  
Heat Exchangers ◽  
Test Results ◽  
Uniform Temperature ◽  
Element Analysis ◽  
Bolt Stress ◽  
Leak Tightness ◽  
Stress Behaviors ◽  
The Impact ◽  
Axisymmetric Temperature

It is critical to maintain uniformity of gasket stress in control against leakage in piping and heat exchangers. Many innovative bolting tools have been developed, but their benefit could be downgraded if there were sources disrupting initially achieved uniformity of gasket stress, especially temperature differences in mating flanges and non-axisymmetric temperature. It is thus necessary to understand behaviors of flanges and gaskets with non-uniform temperature distribution. The impact of temperature differences in mating flanges with various types of gaskets on leak tightness was evaluated by lab tests. Based on test results, 250°F was proposed as a tentative allowable skin temperature difference of mating flanges in heat exchangers. The characteristics of gasket stress behaviors with non-axisymmetric temperature distribution were studied using analytical solution and finite element analysis. It was found that change of gasket stress is independent of the magnitude of initial bolt stress, and initial bolt stress of 50 ksi is sufficient to protect all evaluated flanges against leakage under evaluated non-axisymmetric temperature distributions.

Analysis of Temperature and Heat Flow Characteristics in Underground Tunnel

2014 ◽  
Vol 548-549 ◽  
pp. 579-583
Author(s):  
Hai Min Xie ◽  
Mao De Li
Keyword(s):  
Numerical Simulation ◽  
Temperature Distribution ◽  
Heat Flow ◽  
Thermal Environment ◽  
Flow Characteristics ◽  
Surrounding Rock ◽  
Simplified Model ◽  
Radial Temperature ◽  
Underground Tunnel ◽  
Axial Temperature

This paper summarizes the two methods which are experimental research and numerical simulation to thermal environment of the tunnel. Then the latest developments of the thermal environment research at home and overseas are introduced. At last a simplified model of thermal environment of underground tunnel is established. Through CFD software, the radial temperature distribution of tunnel surrounding rock and the axial temperature distribution of air at winter and summer conditions are obtained which provide basis for further research on thermal environment of underground tunnel.

scholarly journals Stator Non-Uniform Radial Ventilation Design Methodology for a 15 MW Turbo-Synchronous Generator Based on Single Ventilation Duct Subsystem

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2760
Author(s):  
Ruiye Li ◽  
Peng Cheng ◽  
Hai Lan ◽  
Weili Li ◽  
David Gerada ◽  
...  
Keyword(s):  
Finite Element ◽  
Temperature Distribution ◽  
Design Methodology ◽  
Large Scale ◽  
Synchronous Generator ◽  
Axial Direction ◽  
Scale Model ◽  
Element Analysis ◽  
Axial Temperature ◽  
Ventilation Duct

Within large turboalternators, the excessive local temperatures and spatially distributed temperature differences can accelerate the deterioration of electrical insulation as well as lead to deformation of components, which may cause major machine malfunctions. In order to homogenise the stator axial temperature distribution whilst reducing the maximum stator temperature, this paper presents a novel non-uniform radial ventilation ducts design methodology. To reduce the huge computational costs resulting from the large-scale model, the stator is decomposed into several single ventilation duct subsystems (SVDSs) along the axial direction, with each SVDS connected in series with the medium of the air gap flow rate. The calculation of electromagnetic and thermal performances within SVDS are completed by finite element method (FEM) and computational fluid dynamics (CFD), respectively. To improve the optimization efficiency, the radial basis function neural network (RBFNN) model is employed to approximate the finite element analysis, while the novel isometric sampling method (ISM) is designed to trade off the cost and accuracy of the process. It is found that the proposed methodology can provide optimal design schemes of SVDS with uniform axial temperature distribution, and the needed computation cost is markedly reduced. Finally, results based on a 15 MW turboalternator show that the peak temperature can be reduced by 7.3 ∘C (6.4%). The proposed methodology can be applied for the design and optimisation of electromagnetic-thermal coupling of other electrical machines with long axial dimensions.

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