Some comments on heat-transfer laws for fine wires

1972 ◽  
Vol 51 (3) ◽  
pp. 487-495 ◽  
Author(s):  
L. J. S. Bradbury ◽  
I. P. Castro
Keyword(s):  
Heat Transfer ◽  
Time Constants ◽  
Transfer Rates ◽  
Flow Past ◽  
Semi Empirical ◽  
Relationship Of ◽  
The Relationship

The semi-empirical heat-transfer laws of Collis & Williams (1959) and Davies & Fisher (1964) give values of the heat-transfer rates for the flow past fine wires which are generally very different from one another. This paper describes some measurements of heat-transfer and convective time constants which show that the relationship of Collis & Williams is the more representative expression.

Flow Past a Spinning Sphere With Surface Blowing and Heat Transfer

2005 ◽  
Vol 127 (1) ◽  
pp. 163-171 ◽  
Author(s):  
H. Niazmand ◽  
M. Renksizbulut
Keyword(s):  
Heat Transfer ◽  
Three Dimensional ◽  
Flow Regimes ◽  
Solid Sphere ◽  
Temporal Variations ◽  
Transfer Coefficients ◽  
Transfer Rates ◽  
Particle Spin ◽  
Flow Past ◽  
Angular Velocities

Computations are performed to determine the transient three-dimensional heat transfer rates and fluid forces acting on a stream-wise spinning sphere for Reynolds numbers in the range 10⩽Re⩽300 and angular velocities Ωx⩽2. In this Re range, classical flow past a solid sphere develops four different flow regimes, and the effects of particle spin are studied in each regime. Furthermore, the combined effects of particle spin and surface blowing are examined. Sphere spin increases drag in all flow regimes, while lift shows a nonmonotonic behavior. Heat transfer rates are not influenced by spin up to a certain Ωx but increase monotonically thereafter. An interesting feature associated with sphere spin is the development of a special wake regime such that the wake simply spins without temporal variations in its shape. For this flow condition, the magnitudes of the lift, drag, and heat transfer coefficients remain constant in time. Correlations are provided for drag and heat transfer.

scholarly journals Analysis of the coefficient of linear relationship, generated by the exponential heating during the welding process for an A36 steel plate

2021 ◽  
pp. 16-21
Author(s):  
Mario Barrera-Moreno ◽  
Rumualdo Servin-Castañeda ◽  
Ismael Calderon-Ramos ◽  
Alejandro Perez-Alvarado
Keyword(s):  
Heat Transfer ◽  
Steel Plate ◽  
Welding Process ◽  
High Hardness ◽  
Metal Plate ◽  
Filler Material ◽  
A36 Steel ◽  
Welding Sequences ◽  
Relationship Of ◽  
The Relationship

The present study presents the relationship of temperature and deformation as well as the analysis of heat transfer and deformation produced during welding of a steel plate. The method consists of strategically welding a base metal plate (A-36) with a high-hardness filler material to obtain an overall increment in wear resistance. However, the thermal cycles generated during welding produced deformation, thus changing the flatness of the plate. Different sequences of welding were applied to obtain a relationship between the heat transfer and deformation. A filler material was applied to 100 holes (1/2” diameter and 8 mm depth) in a ½” steel plate. The temperature and deformation were measured for 3 different welding sequences. Plate 1 reached a final mean temperature of 467 °C and deformation of 0.016”, plate 2 reached 472.9 °C and -0.008”, and plate 3 reached 354.2 °C and 0.020”. The results indicate that the deformation is not function of the final temperature, instead the deformation is function of the slope of the curve temperature vs deformation. The behavior of the curve temperature vs deformation is linear for all cases studied, confirming the findings of the lowest deformation for plate 2 which exhibited the lowest slope.

scholarly journals МОДЕЛЮВАННЯ ВЗАЄМОДІЇ КРИЛЕВОГО ПРОФІЛЮ З ДОЩОВИМ ПОТОКОМ

2020 ◽  
pp. 36-41
Author(s):  
Сергей Евгеньевич Aгеев ◽  
Юрий Петрович Миляев
Keyword(s):  
Water Film ◽  
Aerodynamic Characteristics ◽  
Negative Consequences ◽  
Wing Profile ◽  
Air Interface ◽  
Adopted Model ◽  
Semi Empirical ◽  
Relationship Of ◽  
Surface Tension Forces ◽  
The Relationship

The subject of the study is the analysis of the multilateral impact of rainfall on the flight of a modern aircraft. When considering various factors of this impact, it was found that the main negative consequences of the interaction of the aircraft with the rain flow are the formation of a thin layer of water on its surface, which under the influence of drops and surface tension forces changes the configuration of the wing profile, causing loss of load-bearing properties and an increase in frontal aircraft resistance. The influence of rain flowing around the bearing surfaces can be reduced to taking into account changes in the characteristics of the surface and the flow of the airflow. The goal is to develop a model for the interaction of modern wing profiles with rain flow. The task is to determine the amount of water deposited on the surface of the wing profile, calculate the parameters of the water film formed on its surface, and as a result of this, change the tangential stress at the liquid-air interface. The semi-empirical calculation method used reveals a significant dependence of the amount of precipitated rain water on the surface of modern wing profiles on their geometry and the conditions of interaction with the stream of raindrops. The result of this work is the resulting model, which allows you to simulate the flow conditions around the wing profile in the rain stream and evaluate the relationship of rain intensity with the parameters of the water film that forms on the profile. Conclusions. An analysis of the features of the rain film flow over the surface of the wing profile and its effect on the parameters of the boundary layer shows the negative nature of the effect of rainfall on the aerodynamics of the aircraft. The results obtained allow us to judge the reliability of using the adopted model to calculate the effect of rain on the aerodynamic characteristics of wing profiles, and the possibility of using the results to determine the dependence of the aerodynamic characteristics of wing profiles on the conditions of rainfall molasses.

The Numerical Simulation of Air-Cooled Plate-Fin Heat Exchanger

2011 ◽  
Vol 314-316 ◽  
pp. 1472-1477 ◽  
Author(s):  
Xue Jiang ◽  
Ji Hua Bao ◽  
Yan Yu ◽  
Ming Xia Gu
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Heat Exchanger ◽  
3D Model ◽  
Fluid Velocity ◽  
Heat Transfer Characteristics ◽  
Flow And Heat Transfer ◽  
Simulation Results ◽  
Relationship Of ◽  
The Relationship

According to the periodic structure of the plate-fin heat exchanger, 3D model of the heat exchanger is established which simplifies the computation amount of the numerical simulation on flow field and temperature field. The relationship of fluid velocity, temperature, pressure drop and heat transfer coefficient is analyzed. The flow and heat transfer characteristics can be well predicted. Based on the simulation results, the conclusion makes reference to the design of plate-fin heat exchanger.

The Relationship of the External Surface Area of Birds to Skin Surface Area and Body Mass

1978 ◽  
Vol 76 (1) ◽  
pp. 185-189 ◽  
Author(s):  
GLENN E. WALSBERG
Keyword(s):  
Heat Transfer ◽  
Surface Area ◽  
Body Mass ◽  
External Surface ◽  
Bird Species ◽  
Skin Surface ◽  
External Surface Area ◽  
Relationship Of ◽  
The Relationship

Data from 12 bird species reveal that skin surface area averages 23 % larger than the external surface area of the plumage. Use of skin surface area instead of the area of the external plumage surface may produce large errors in heat-transfer analyses.

Turbulent Boundary Layer and Heat Transfer Measurements Along a Convergent-Divergent Nozzle

1971 ◽  
Vol 93 (4) ◽  
pp. 397-407 ◽  
Author(s):  
L. H. Back ◽  
R. F. Cuffel
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Reynolds Number ◽  
Friction Coefficient ◽  
Energy Equation ◽  
Integral Form ◽  
Conical Nozzle ◽  
Half Angle ◽  
Semi Empirical ◽  
The Relationship

Boundary layer and heat transfer measurements are presented along a cooled, conical nozzle with a convergent and a divergent half-angle of 10 deg. Semi-empirical analyses are considered in conjunction with the measurements. The heat transfer is found to be describable by using the integral form of the energy equation once the relationship between the Stanton number and energy thickness Reynolds number has been established from the measurements. The friction coefficient, however, is not described accurately along the entire nozzle by existing formulations considered.

Model Simulating the Heat Transfer of Skin

2014 ◽  
Vol 3 (2) ◽  
pp. 42-58 ◽  
Author(s):  
Anders Jarløv ◽  
Tim Toftgaard Jensen
Keyword(s):  
Heat Transfer ◽  
Human Skin ◽  
Blood Perfusion ◽  
Electrical Model ◽  
Skin Model ◽  
Transfer Rates ◽  
Electric Circuits ◽  
Analogue Models ◽  
The Relationship

The relationship between surface temperature and heat transfer in a section of isotropic material with plane parallel sides, in this context simulating human skin, can be attained by means of analogue models. A model, in the form of electric circuits, enables the analogue functions to be recorded as electrical signals. Analogue heat transfer rates derived by processing voltage data from the models can be used for the determination of analogue measures of blood perfusion of the skin, which is generally stated in terms of ml blood flow per 100 ml tissue per minute. Analogue time scales can be compressed, reducing recording times of analogue functions, and inaccessible sites of actual tissues can be made accessible for observation in a model version. Lengthy calculations and the development of formulas can be substituted with the recording of analogue functions. The ability of a perfusable material to simulate the skin model is estimated by how well the material, when subjected to known perfusions with water, exhibit surface temperatures that agree with the corresponding analogue properties of the electrical model. The materials and methods are tentatively applied to recordings of perfusion of human skin.

M806 The Relationship of Heat Transfer Characteristics and Structures in Wood

2015 ◽  
Vol 2015.90 (0) ◽  
pp. 370
Author(s):  
Takayuki MASUDA ◽  
Yoshiki NOGUCHI ◽  
Yoichi SHIOMI ◽  
Daisuke TAWARA
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Relationship Of ◽  
The Relationship
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