Wyniki wyszukiwania - BazTech

1

Badania numeryczne mechanicznego usuwania termicznej warstwy przyściennej dla nieskończonej kaskady łopatek skrobiących

Błasiak P.

Technical Issues

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2015

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nr 1

13--21

EN

The aim of the study is to examine the impact of the gap between the tip of the scraping blade (scraper) and the wall on the heat transfer. Numerical simulations of heat transfer and fluid flow under mechanical removing of thermal boundary layer were conducted. Due to the complexity of the phenomenon calculations were simplified to the two-dimensional case. As a test case a heat transfer under removing thermal boundary layer via infinite, rectangular scrapers cascade was chosen. Calculations were carried out for different scraper heights, ie. for different gap values. Reynolds and Grashof numbers were constant and equalled 1000 and 10 000 respectively. The range of Prandtl number and the gap varied 0.7-56.0 and 0.005L-0.25L accordingly. The results showed that heat transfer intensification increases with the increasing Prandtl. It was shown that gap value strongly influences both temperature distribution and heat transfer rate. With the decreasing gap heat transfer rate increases.

2

Zastosowanie analogii cieplno-elektrycznej do wyznaczenia własności cieplnych kręgu blachy

Wyczółkowski R., Piechowicz Ł., Benduch A

Modelowanie Inżynierskie

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2013

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T. 15, nr 46

121--126

EN

The article presents a methodology for computation of the radial effective thermal conductivity λr of a coil of steel sheet. This quantity constitutes one of the conditions of uniqueness in analytical solving of the problem of heating steel strip in the form of coils. The obtained results indicate that the value of the coefficient λr varies within a wide range and is dependent on a number of various parameters. The lack of detailed knowledge on the variation of the value of this coefficient may be the cause of significant errors in modelling steel sheet coil heating and cooling processes.

PL

W artykule przedstawiono metodykę obliczania promieniowej efektywnej przewodności cieplnej λr kręgu stalowej blachy. Wielkość ta stanowi jeden z warunków jednoznaczności przy analitycznym rozwiązywaniu problemu nagrzewania stalowej taśmy w postaci kręgów. Otrzymane wyniki pokazują, iż wartość współczynnika λr zmienia się w szerokich granicach i uzależniona jest od szeregu różnych parametrów. Brak dokładnej wiedzy na temat kształtowania się wartości tego współczynnika może być przyczyną istotnych błędów przy modelowaniu procesów nagrzewania i chłodzenia kręgów stalowej blachy.

3

A model of heat transfer taking place in thermographic test stand

Kaczmarczyk J., Rojek M., Wróbel G., Stabik J.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

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Vol. 27, nr 1

7-14

EN

Purpose: The aim of this paper is to present a model describing heat transfer taking place during thermovision testing of polymer composites. Thermographic tests were undertaken to identify thermal properties of searched material and to correlate them with operational characteristics. Design/methodology/approach: Heat transfer model of thermographic testing stand of our own design was elaborated. The model was applied as a tool of tested material characteristics identification, forming the basis of laminate degradation degree diagnosis. Findings: The most essential result of the project is the physical heat transfer model. Good conformity between model predictions and exemplary experimental results was achieved. The set of physical characteristics describing thermal state of composite was identified and introduced into the model. Research limitations/implications: Experimental results of heat transfer through the composite mounted in thermographic testing stand proved the correctness of developed model. Results of physical properties identification showed the possibility of non-destructive diagnosis of wide class of materials, namely polymeric composites. Practical implications: Results of presented project together with results of planned experimental programme devoted to elaboration of diagnostic relations enable to apply thermography directly to the state of polymeric structural materials assessment. Especially the degree of material degradation may be estimated. Originality/value: Originality of the project is based on possibility of practical application of the model to simulate heat transfer through tested sample mounted in thermographic test stand. Proposed scope of diagnostic tests was not interesting for scientists till now.

4

Szacowanie gradientu w analitycznym i numerycznym rozwiązaniu pola temperatury

Mikołajczak P., Ignaszak Z.

Archiwum Odlewnictwa

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2002

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R. 2, nr 4

147--154

PL

Przeprowadzono porównanie analitycznego i numerycznego rozwiązania dla klasycznego układu cieplnego odlew-forma pół-przestrzenna. Otrzymane wyniki odniesiono do pomiarów eksperymentalnych. Wskazano na przyczyny rozbieżności między dwoma sposobami rozwiązań oraz czynniki wpływające na dokładność przybliżenia gradientów temperatury. Rozważania prowadzono w aspekcie zastosowania gradientów temperatury do obliczeń wielkości kryterialnych, służących podczas oceny jakości odlewu w post-processingowych procedurach systemów symulacyjnych.

EN

The comparison between analytical and numerical solutions for the classic thermal system casting-mould (as half space) was carried out. Obtained results were compared with experimental data. The divergences depending on the method of heat transfer modeling were shown. The factors affecting accuracy of the local temperature gradient were analysed. The analysis was carried out in aspect of using the temperature gradient for criterial parameters calculation applied in post-processing casting quality estimation.