On some steady state temperature fields in semiinfinite solids with cylindrical heat sources

1965 ◽  
Vol 8 (6) ◽  
pp. 496-498 ◽  
Author(s):  
D. A. Pereverzev
Keyword(s):  
Steady State ◽  
Temperature Fields ◽  
Heat Sources ◽  
Steady State Temperature

Transient Damped Wave Conduction and Relaxation in Human Skin and Thermal Wear During Winter

2008 ◽  
Author(s):  
Kal Renganathan Sharma
Keyword(s):  
Steady State ◽  
Human Skin ◽  
Separation Of Variables ◽  
Relaxation Times ◽  
Thermal Relaxation ◽  
Transient Temperature ◽  
Heat Sources ◽  
Maximum Heat ◽  
Steady State Temperature ◽  
Fabric Layer

Damped wave conduction and relaxation in the human skin layer and thermal fabric layer are modeled with a temperature dependent heat source in the human tissue layer. Steady state temperature profiles are derived from the Fourier heat conduction equation. The general solution for the temperature is assumed to be a sum of the transient temperature and steady state temperature. This makes the boundary conditions in space for the skin and fabric layers homogeneous for the transient temperarature. The hyperbolic PDE is solved for by the method of separation of variables. The use of final condition in time in addition to the initial temperature condition leads to bounded infinite Fourier series solutions. These solutions are bounded and does not violate second law of thermodynamics. The model can be used to interpret experimental observations of maximum heat flux that is a parameter of the warm/cool feeling of human skin in winter. For large relaxation times of human skin tissue, τrs>(1+U*)2(b−a)216π2αs, the transient temperature can be expected to undergo oscillations. These oscillations will be supercritical and grow with time for strong heat sources, U* > 1 and may be subcritical damped oscillatory for weak heat sources, U* < 1. For large thermal relaxation times of thermal fabric material, τrf>a24π2αs, the transient temperature in the thermal fabric layer may be expected to be subcritical damped oscillatory.

scholarly journals Vibration Response Analysis of a Gear-rotor-bearing System Considering Steady-state Temperature

2021 ◽  
Author(s):  
Zhou Sun ◽  
Siyu Chen ◽  
Zehua Hu ◽  
Duncai Lei
Keyword(s):  
Steady State ◽  
Material Properties ◽  
Temperature Fields ◽  
Response Analysis ◽  
Nodal Method ◽  
Steady State Temperature ◽  
Rotor Bearing ◽  
Influence Of Temperature On ◽  
Bearing Force ◽  
Bearing System

Abstract As an important factor leading to the failure of gear system, the study of thermal effect is insufficiently deep. Based on the finite element nodal method, a more comprehensive dynamic model of gear-rotor-bearing system is established, which considers the thermal related material properties, time-varying meshing stiffness (TVMS), backlash and friction, gyroscopic effect. The constitutive relation of beam element considering steady-state temperature is reconstructed, and thermal node load is formulated. Considering the influence of temperature on the material properties of flexible shaft and gear, the thermal related TVMS and thermal backlash are obtained. The dynamic response of the system under different steady-state temperature fields is compared, and the influence of hot backlash is studied, then the thermal related vibration characteristics are obtained. Besides, the influence of bearing type on bearing force and axial trajectory is studied. The results show that the system motion changes from period to chaos with the temperature increase in part of the speed range. The appropriate backlash is helpful to restrain the chaotic motion caused by temperature rise. Moreover, the temperature can significantly increase the axial bearing force, and the appropriate bearing can reduce the axial displacement.

scholarly journals Mathematical models of steady-state temperature fields produced by multi-piped freezing

2016 ◽  
Vol 17 (9) ◽  
pp. 702-723 ◽  
Author(s):  
Xiang-dong Hu ◽  
Wang Guo ◽  
Luo-yu Zhang ◽  
Jin-tai Wang ◽  
Xue Dong
Keyword(s):  
Steady State ◽  
Mathematical Models ◽  
Temperature Fields ◽  
Steady State Temperature

Heat Transfer Finite Element Analysis of an Adhesive Bonding Process

1995 ◽  
Author(s):  
Roger L. Veldman ◽  
Dennis J. VandenBrink
Keyword(s):  
Finite Element ◽  
Steady State ◽  
Adhesive Bonding ◽  
Adhesive Layer ◽  
Bonding Process ◽  
Heat Sources ◽  
Element Analysis ◽  
Steady State Condition ◽  
Steady State Temperature ◽  
Time Required

Abstract The finite element method was used to model an adhesive bonding process between a sheet of glass and a long strip of flexible PVC. The effect of the thickness of the PVC strip, the number of heat sources, the temperature of the heat sources, the size of the heat sources, and convection on the steady state temperature distribution in the adhesive layer was studied. The time required to reach the steady-state condition was also determined.

Numerical Calculation of Non-Steady-State Temperature Fields in Oblique Cutting

CIRP Annals ◽  
1983 ◽  
Vol 32 (1) ◽  
pp. 43-46 ◽  
Author(s):  
V.A. Ostafiev ◽  
A.A. Cherniavskaya ◽  
V.A. Sinopalnikov ◽  
T.N. Loladze
Keyword(s):  
Steady State ◽  
Numerical Calculation ◽  
Temperature Fields ◽  
Oblique Cutting ◽  
Steady State Temperature

scholarly journals Identification of DC Thermal Steady-State Differential Inductance of Ferrite Power Inductors

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3854
Author(s):  
Salvatore Musumeci ◽  
Luigi Solimene ◽  
Carlo Stefano Ragusa
Keyword(s):  
Steady State ◽  
Input Voltage ◽  
Switching Frequency ◽  
Ohmic Losses ◽  
Steady State Temperature ◽  
Wide Range ◽  
Average Current ◽  
Power Inductors ◽  
Saturable Inductor ◽  
Thermal Steady State

In this paper, we propose a method for the identification of the differential inductance of saturable ferrite inductors adopted in DC–DC converters, considering the influence of the operating temperature. The inductor temperature rise is caused mainly by its losses, neglecting the heating contribution by the other components forming the converter layout. When the ohmic losses caused by the average current represent the principal portion of the inductor power losses, the steady-state temperature of the component can be related to the average current value. Under this assumption, usual for saturable inductors in DC–DC converters, the presented experimental setup and characterization method allow identifying a DC thermal steady-state differential inductance profile of a ferrite inductor. The curve is obtained from experimental measurements of the inductor voltage and current waveforms, at different average current values, that lead the component to operate from the linear region of the magnetization curve up to the saturation. The obtained inductance profile can be adopted to simulate the current waveform of a saturable inductor in a DC–DC converter, providing accurate results under a wide range of switching frequency, input voltage, duty cycle, and output current values.

Development of Convective Heat Transfer Near Suddenly Heated, Vertically Aligned Horizontal Wires

1987 ◽  
Vol 109 (4) ◽  
pp. 912-918 ◽  
Author(s):  
J. R. Parsons ◽  
M. L. Arey
Keyword(s):  
Heat Transfer ◽  
Heat Source ◽  
Fluid Layer ◽  
Convective Motion ◽  
Transient Behavior ◽  
Temperature Fields ◽  
Heat Sources ◽  
Transfer Coefficients ◽  
Vertically Aligned ◽  
The Wire

Experiments have been performed which describe the transient development of natural convective flow from both a single and two vertically aligned horizontal cylindrical heat sources. The temperature of the wire heat sources was monitored with a resistance bridge arrangement while the development of the flow field was observed optically with a Mach–Zehnder interferometer. Results for the single wire show that after an initial regime where the wire temperature follows pure conductive response to a motionless fluid, two types of fluid motion will begin. The first is characterized as a local buoyancy, wherein the heated fluid adjacent to the wire begins to rise. The second is the onset of global convective motion, this being governed by the thermal stability of the fluid layer immediately above the cylinder. The interaction of these two motions is dependent on the heating rate and relative heat capacities of the cylinder and fluid, and governs whether the temperature response will exceed the steady value during the transient (overshoot). The two heat source experiments show that the merging of the two developing temperature fields is hydrodynamically stabilizing and thermally insulating. For small spacing-to-diameter ratios, the development of convective motion is delayed and the heat transfer coefficients degraded by the proximity of another heat source. For larger spacings, the transient behavior approaches that of a single isolated cylinder.

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