The Effects of Kinetic Heating on Aircraft Structures

1958 ◽  
Vol 62 (566) ◽  
pp. 105-117 ◽  
Author(s):  
A. W. Kitchenside
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
High Temperature ◽  
Structural Analysis ◽  
Current Practice ◽  
Structural Materials ◽  
Boundary Layer Theory ◽  
Supersonic Flight ◽  
Aircraft Structures ◽  
Structural Engineer

Kinetic heating, which is associated with supersonic flight, is probably the greatest challenge which has confronted the structural engineer, since the design and analysis of affected structures requires a radical extension of current practice. For example, the laws of heat transfer and the effects of high temperature on structural materials become important factors in structural analysis. To obtain a clear appreciation of the situation it is therefore necessary for the designers of the structure to become familiar with these factors, together with certain aspects of boundary layer theory.

Development of High Temperature Liquid Metal Heat Transfer Fluids for CSP Applications

2014 ◽  
Author(s):  
Gopinath R. Warrier ◽  
Y. Sungtaek Ju ◽  
Jan Schroers ◽  
Mark Asta ◽  
Peter Hosemann
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Liquid Metal ◽  
Liquid Metals ◽  
Research Effort ◽  
Structural Materials ◽  
Forced Flow ◽  
Oxygen Control ◽  
Ongoing Research ◽  
Heat Transfer Fluids

In response to the DOE Sunshot Initiative to develop low-cost, high efficiency CSP systems, UCLA is leading a multi-university research effort to develop new high temperature heat transfer fluids capable of stable operation at 800°C and above. Due to their operating temperature range, desirable heat transfer properties and very low vapor pressure, liquid metals were chosen as the heat transfer fluid. An overview of the ongoing research effort is presented. Development of new liquid metal coolants begins with identification of suitable candidate metals and their alloys. Initial selection of candidate metals was based on such parameters as melting temperature, cost, toxicity, stability/reactivity Combinatorial sputtering of the down selected candidate metals is used to fabricate large compositional spaces (∼ 800), which are then characterized using high-throughput techniques (e.g., X-ray diffraction). Massively parallel optical methods are used to determine melting temperatures. Thermochemical modeling is also performed concurrently to compliment the experimental efforts and identify candidate multicomponent alloy systems that best match the targeted properties. The modeling effort makes use of available thermodynamic databases, the computational thermodynamic CALPHAD framework and molecular-dynamics simulations of molten alloys. Refinement of available thermodynamics models are performed by comparison with available experimental data. Characterizing corrosion in structural materials such as steels, when using liquid metals, and strategies to mitigate them are an integral part of this study. The corrosion mitigation strategy we have adopted is based on the formation of stable oxide layers on the structural metal surface which prevents further corrosion. As such oxygen control is crucial in such liquid metal systems. Liquid metal enhanced creep and embrittlement in commonly used structural materials are also being investigated. Experiments with oxygen control are ongoing to evaluate what structural materials can be used with liquid metals. Characterization of the heat transfer during forced flow is another key component of the study. Both experiments and modeling efforts have been initiated. Key results from experiments and modeling performed over the last year are highlighted and discussed.

Utilizing the Integral Technique to Determine the Similarity Variable in Classical Heat Transfer Problems: One Dimensional Heat Conduction in a Finite or Semi-Infinite Solid

2013 ◽  
Author(s):  
Chris J. Kobus
Keyword(s):  
Heat Transfer ◽  
Differential Equation ◽  
Boundary Layer ◽  
Variable Temperature ◽  
Boundary Layer Theory ◽  
Good Tool ◽  
Similarity Variable ◽  
Integral Technique ◽  
Independent Variable ◽  
Transfer Problems

In advanced heat transfer courses, a technique exists for reducing a partial differential equation where the dependent variable is a function of two independent variables, to an ordinary differential equation where that same dependent variable becomes a function of only one independent variable. The key to this technique is finding out what the similarity variable to make this transformation is. The difficulty is that the form of the similarity variable is not intuitive, and many heat transfer textbooks do not reveal how this variable is found in classical problems such as viscous and thermal boundary layer theory. It turns out that one way to find this variable is by utilizing the integral technique. By employing the integral technique to boundary layer theory, it will be shown that when the approximate functional relationship for the dependent variable (temperature, velocity, etc) can be represented by an nth order polynomial, the similarity variable can be found very simply. This is seen to be a good tool especially in heat transfer education, but has applications in research as well.

scholarly journals The Effect of Roughness on the Rate of Ice Accretion on a Cylinder

1985 ◽  
Vol 6 ◽  
pp. 142-145
Author(s):  
Lasse Makkonen ◽  
J. R. Stallabrass
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Theoretical Model ◽  
Wind Tunnel ◽  
Empirical Data ◽  
Transfer Rate ◽  
Growth Conditions ◽  
Boundary Layer Theory ◽  
Freezing Process ◽  
Ice Accretion

The rate of icing in the wet growth conditions typical of ship icing and icing in freezing precipitation depends on the rate at which the heat liberated in the freezing process is transferred to the environment. A theoretical model for the heat transfer from the front half of a rough cylinder, based on boundary-layer theory, is described. Comparisons with empirical data show that the model simulates well the overall heat transfer rate from the front half of a cylinder with distributed roughness. The theory provides improved agreement between the results of a numerical icing model and icing wind tunnel tests.

Boundary-layer theory for blast waves

1975 ◽  
Vol 71 (1) ◽  
pp. 65-88 ◽  
Author(s):  
K. B. Kim ◽  
S. A. Berger ◽  
M. M. Kamel ◽  
V. P. Korobeinikov ◽  
A. K. Oppenheim
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Flow Field ◽  
Classical Problem ◽  
Outer Region ◽  
Inviscid Flow ◽  
Boundary Layer Theory ◽  
Blast Waves ◽  
Matched Asymptotic Expansion ◽  
Flow Equations

The necessity for developing a boundary-layer theory in the case of blast waves stems from the fact that inviscid flow solutions often yield physically unrealistic results. For example, in the classical problem of the so-called non-zero counterpressure explosion, one obtains infinite temperature and zero density in the centre at all times even after the shock front deteriorates into a sound wave. In reality, this does not occur, as a consequence, primarily, of heat transfer that modifies the structure of the flow field around the centre without drastically affecting the outer region. It is profitable, therefore, to consider the blast wave as a flow field consisting of two regions: the outer, which retains the properties of the inviscid solution, and the inner, which is governed by flow equations including terms expressing the effects of heat transfer and, concomitantly, viscosity. The latter region thus plays the role of a boundary layer. Reported here is an analytical method developed for the study of such layers, based on the matched asymptotic expansion technique combined with patched solutions.

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