Growth of Tilted Domains in an Octadecanol Langmuir Monolayer Using Radial Temperature Gradients

2004 ◽  
Vol 108 (36) ◽  
pp. 13696-13699 ◽  
Author(s):  
Z. Khattari ◽  
Th. M. Fischer
Keyword(s):  
Langmuir Monolayer ◽  
Temperature Gradients ◽  
Radial Temperature

Modeling of Thermal Stresses and Thermal Cracking During Heating of Large Ingots

1996 ◽  
Vol 118 (2) ◽  
pp. 235-243 ◽  
Author(s):  
M. K. Alam ◽  
R. L. Goetz ◽  
S. L. Semiatin
Keyword(s):  
Thermal Stresses ◽  
Titanium Aluminides ◽  
Temperature Gradients ◽  
End Effects ◽  
Radial Temperature ◽  
Stress Criterion ◽  
Intermetallic Materials ◽  
Analytical Series ◽  
Biot Numbers ◽  
Selection Of

The development of temperature gradients and thermal stresses during the heating of large ingots has been investigated with special reference to the selection of heating schedules for brittle intermetallic materials such as titanium aluminides. A 1-D analytical (series) solution for radial temperature transients was used in conjunction with an elasticity analysis to determine the maximum thermal stresses that would be generated during ingot heating. The temperature gradients and stresses were seen to be strongly dependent on Fourier and Biot Numbers. In addition, finite element method simulations incorporating end effects and variations of thermal and elastic properties with temperature were performed and compared to the analytical results. Comparison of the predicated thermal stresses and actual ingot heating observations suggest that cracking is controlled by a maximum normal stress criterion.

A NUMERICAL INVESTIGATION OF THE FLOW IN A FULLY BLOCKED DIFFERENTIALLY HEATED ROTATING FLUID ANNULUS

1994 ◽  
Vol 05 (02) ◽  
pp. 203-206 ◽  
Author(s):  
Q.G. RAYER
Keyword(s):  
Computational Model ◽  
Horizontal Plane ◽  
Computer Modelling ◽  
Temperature Gradients ◽  
Rotating Fluid ◽  
Dynamical Equations ◽  
Radial Temperature ◽  
Rotation Rates ◽  
Horizontal Circulation ◽  
Simply Connected

A computational model has been used to determine the terms in the dynamical equations which are responsible for the formation of a certain horizontal circulation seen in a simply connected, differentially heated rotating fluid annulus. Experiments with a differentially heated rotating fluid annulus that is fully blocked by a thin, rigid, vertical radial barrier at rotation rates of up to 5 rad.sec−1 and with an externally applied radial temperature difference of 4 or 10 °C show two principal circulations. This paper is concerned with the mechanism for one of those circulations, which occurs in a horizontal plane. Computer modelling shows that this circulation is caused by small radial temperature gradients in the fluid, rather than centrifugal effects.

Thermo-mechanical stress analysis of rotating fiber reinforced variable thickness disk

2021 ◽  
pp. 030932472110609
Author(s):  
Ömer Can Farukoğlu ◽  
İhsan Korkut
Keyword(s):  
Variable Thickness ◽  
Failure Criteria ◽  
Temperature Gradients ◽  
Fiber Reinforced ◽  
Displacement Fields ◽  
Disk Radius ◽  
Radial Temperature ◽  
Stress And Displacement Fields ◽  
Angular Velocities ◽  
Analytical Approaches

Circumferentially fiber reinforced composite disk, which has a variable thickness, is modeled via analytical approaches. The disk is subjected to rotation in traction free conditions and decreasing, constant, and increasing steady state radial temperature gradients along the disk radius. Limit angular velocities are calculated by operating Tsai-Wu and Norris failure indexes to the problem. Subsequently, these limit velocities are gradually decreased to examine the stress and displacement fields. Acquired results show that as the angular velocity drops, the effects of temperature gradients become more visible. At lower angular velocities, these gradients may even alter the stress field directions. Also, different failure criteria implementation may change the calculated limit velocities to a considerable degree. Therefore, the failure index should be chosen attentively to procure conservative results. In the investigation, the influence of disk geometry on the directional stresses is studied as well. Without further ado, it can be expressed that the geometry causes slight alterations in stresses and displacements.

Infrared Imaging of 2-D Temperature Distribution During Cryogen Spray Cooling

2002 ◽  
Vol 124 (6) ◽  
pp. 669-675 ◽  
Author(s):  
Bernard Choi ◽  
Ashley J. Welch
Keyword(s):  
Temperature Distribution ◽  
Spray Cooling ◽  
Temperature Gradients ◽  
Measured Temperature ◽  
Back Side ◽  
Surface Cooling ◽  
Radial Temperature ◽  
Cooling Temperature ◽  
Temperature Distributions ◽  
Cryogen Spray Cooling

Cryogen spray cooling (CSC) is used in conjunction with pulsed laser irradiation for treatment of dermatologic indications. The main goal of this study was to determine the radial temperature distribution created by CSC and evaluate the importance of radial temperature gradients upon the subsequent analysis of tissue cooling throughout the skin. Since direct measurement of surface temperatures during CSC are hindered by the formation of a liquid cryogen layer, temperature distributions were estimated using a thin, black aluminum sheet. An infrared focal plane array camera was used to determine the 2-D backside temperature distribution during a cryogen spurt, which preliminary measurements have shown is a good indicator of the front-side temperature distribution. The measured temperature distribution was approximately gaussian in shape. Next, the transient temperature distributions in skin were calculated for two cases: 1) the standard 1-D solution which assumes a uniform cooling temperature distribution, and 2) a 2-D solution using a nonuniform surface cooling temperature distribution based upon the back-side infrared temperature measurements. At the end of a 100-ms cryogen spurt, calculations showed that, for the two cases, large discrepancies in temperatures at the surface and at a 60-μm depth were found at radii greater than 2.5 mm. These results suggest that it is necessary to consider radial temperature gradients during cryogen spray cooling of tissue.

scholarly journals Unsteady Numerical Simulations of Radial Temperature Profile Redistribution in a Single-Stage Turbine

1995 ◽  
Author(s):  
Daniel J. Dorney ◽  
John R. Schwab
Keyword(s):  
Experimental Data ◽  
Temperature Profile ◽  
Total Pressure ◽  
Three Dimensional ◽  
Temperature Gradients ◽  
Single Stage ◽  
Angle Distribution ◽  
Pressure Gradients ◽  
Flow Angle ◽  
Radial Temperature

Experimental data taken from gas turbine combustors indicate that the flow exiting the combustor can contain both circumferential and radial temperature gradients. A significant amount of research recently has been devoted to studying turbine flows with inlet temperature gradients, but no total pressure gradients. Less attention has been given to flows containing both temperature and total pressure gradients at the inlet. The significance of the total pressure gradients is that the secondary flows and the temperature redistribution process in the vane blade row can be significantly altered. Experimental data previously obtained in a single-stage turbine with inlet total temperature and total pressure gradients indicated a redistribution of the warmer fluid to the pressure surface of the airfoils, and a severe underturning of the flow at the exit of the stage. In a concurrent numerical simulation, a steady, inviscid, three-dimensional flow analysis was able to capture the redistribution process, but not the exit flow angle distribution. In the current research program, a series of unsteady two- and three-dimensional Navier-Stokes simulations have been performed to study the redistribution of the radial temperature profile in the turbine stage. The three-dimensional analysis predicts both the temperature redistribution and the flow underturning observed in the experiments.

Transient Heat Transfer in a Packed-Bed Elliptic Cylindrical Reactor: A Finite-Volume Approach

2017 ◽  
Vol 380 ◽  
pp. 79-85 ◽  
Author(s):  
R. Moura da Silva ◽  
A.G. Barbosa de Lima ◽  
L. Gomes de Oliveira ◽  
Morgana Vasconcellos Araújo ◽  
R.S. Santos
Keyword(s):  
Heat Transfer ◽  
Temperature Profile ◽  
Heat Transfer Rate ◽  
Finite Volume ◽  
Transfer Rate ◽  
Temperature Gradients ◽  
Fixed Bed Reactor ◽  
Radial Temperature ◽  
Maximum Heat ◽  
Reactor Surface

This work aims to develop a transient three-dimensional mathematical model using the elliptic cylindrical coordinate system, to predict heat transfer in a elliptic cylindrical packed fixed bed reactor. The model considers variable thermo physical properties and a parabolic temperature profile at the fluid inlet. The governing equation is solved using the finite volume method. Results of temperature profile along the reactor are presented and discussed at different moments.It was verified that the maximum heat transfer rate inside the reactor occurs near the extreme region close to minor semi-axis of the ellipse; the higher temperatures at the reactor surface are also in this region, along the entire height of the bed; the steady-state regime is reached at t = 4.5 s of process, presenting after this time interval,small axial temperature gradients and high radial gradients along of the reactor bed; the parabolic temperature profile give to the bed a predominance of radial temperature gradients, and the radial porosity profile favours a higher heat transfer rate at reactor surface.

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