IMPACT OF THE HIGH-SPEED FLOW OF POWDER PARTICLES ON THE STRUCTURE OF POLYMER MATERIALS AND METAL-POLYMER COMPOSITES

Author(s):  
Yulia Usherenko ◽  
Viktors Mironovs ◽  
Leonids Pakrastiņš

The problem of protecting spacecraft from cosmic dust has recently come to the fore. There is still no enough data on the complex effect of short-term high-energy, dynamic loading on materials, including polymer materials and multilayer polymer-metal composites. The use of dynamic alloying in the super-deep penetration (SDP) mode by high-speed flows of powder particles allows assessing the effect on the material under dynamic action. Previous studies on steel and aluminum samples have shown a significant effect of high-speed flows of powder particles on the structure and properties of materials. As a result of a study of samples made of aliphatic polyurethane with steel reinforcement elements, it was found that there are traces of the penetration of high-speed particles into both metal and polymer layers. However, the number of flow elements detected in the polymeric part is significantly less than the number of elements in the metal reinforcing part. Thus, it is possible to assume that or the polymer material is a more effective barrier to the high-speed flow compared to the metal, or the “self-healing” effect is observed. 

2008 ◽  
Vol 53 (15) ◽  
pp. 2371-2375 ◽  
Author(s):  
LingQian Zhang ◽  
ZhenXing Liu ◽  
ZhiWei Ma ◽  
W. Baumjohann ◽  
M. W. Dunlop ◽  
...  

Author(s):  
Maximilian Passmann ◽  
Stefan aus der Wiesche ◽  
Eugeny Y. Kenig

Abstract Low speed and high speed flow phenomena in pillow plate channels are considered. High speed flows were investigated by means of analytical methods and fully three-dimensional computational fluid dynamics (CFD) simulations. The theoretical analysis indicated that a Fanno-type flow model described high speed flow behavior in pillow plate channels reasonably well. Since only wavy walls with smooth profiles were involved, linearized gas dynamics was applied in order to derive similarity laws for the high speed flows. The detailed CFD analysis was used to support the assumption of a Fanno-type flow. The effects of the wavy wall structures on pressure drop and Mach number distribution within the flow path were investigated in detail. The present analysis demonstrates that pillow plate heat exchangers represent promising candidates for high speed turbo machinery applications.


Author(s):  
C. Kannepalli ◽  
S. Arunajatesan ◽  
W. H. Calhoon ◽  
S. M. Dash

RANS models are required for the prediction of scalar fluctuations and turbulent transport in the high speed flow regime. These models will have application, for example, in missile exhaust plume signature analyses, scramjet combustors and other important areas. However, experimentally derived scalar fluctuation data needed to develop these models for the high speed flow regime is not readily available due to the inability of relevant experimental measurement techniques (e.g. hot wires) to cope with this flowfield environment. This issue poses significant difficulties for model development in this flow regime. Researchers have used different values for the turbulent Prandtl and Schmidt numbers but no consensus has been reached as to what these values have to be for high speed flows. To address this difficulty, a two part program has been initiated to fill the data gap and thus facilitate model development. Part I of this program involves the collection of LES data over a wide range of conditions. Part II involves the use of these data to evaluate and develop RANS tools to improve predictive capabilities. This paper presents results and findings of Part I of this program. Several flow fields of relevance to the problems mentioned above are studied. These include classical unit problems such as high and low Mach number shear layers, boundary layers and separated flows such as compression corner flows. In the process we are gradually extending the applicability of LES to more complex flows and at the same time enabling RANS model development by facilitating flow databases in the high speed flight regime. The findings of this study elucidate the effects of compressibility on the character of mean scalar profiles, variations in turbulent Prandtl number, and on scalar rms fluctuations.


Author(s):  
Nicholas Findanis

Abstract Flows in manifolds is a ubiquitous and important area to implement flow improvements. In almost all applications of industrial pipe flows, there is the requirement to distribute the flow of fluid. There is a deficiency of studies in the area of flow distribution in manifolds with high speed flows. The present work is aimed at providing a further understanding of transient high speed flow distribution in manifolds. The different manifold configurations were analysed computationally. A comparison was focused between through the different aspect ratio manifolds. The velocity field and the eddy viscosity parameters where compared between the simulated flow models to ascertain the key features in the distributed flow field and especially, to determine the areas that showed greater flow recirculation or flow eddies and the separated flow regions. The CFD study was conducted as a high speed flow/ compressible flow regime accounting for the ideal gas dynamic model being air as the working fluid. The study showed that the transient behaviour of flow field can significantly affect distribution of the flow depending on the aspect ratio and number of branches on the manifold. Efficiency gains can be achieved in high speed flows that can be of benefit in industrial and other engineered flow applications.


1969 ◽  
Vol 40 (9) ◽  
pp. 3563-3573 ◽  
Author(s):  
Terrill A. Cool

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