Wyniki wyszukiwania - BazTech

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Analiza pośrednich i bezpośrednich obiegów wyparnych w systemach SDEC. Wyniki symulacji numerycznej

Pandelidis D.

Chłodnictwo : organ Naczelnej Organizacji Technicznej

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2013

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R. 48, nr 6

30--34

PL

W drugiej części artykułu zaprezentowano wyniki symulacji numerycznej, obrazującej prace trzech pośrednich wymienników wyparnych w systemach SDEC (rekuperator o krzyżowym, przeciwprądowym i regeneracyjnym schemacie przepływie powietrza). Przedstawiono charakterystyczne cechy poszczególnych urządzeń oraz ich wady i zalety w kontekście pracy w układach SDEC. Dokonano analizy porównawczej z klasycznymi układami opartymi na komorach zraszania.

EN

The second part of the article presents the results of numerical simulation illustrating the work of three indirect evaporative coolers used in SDEC systems (recuperators with cross, counter and regenerative air flow diagram). Individual characteristics of considered devices have been presented and their advantages and disadvantages in the context of the work in SDEC systems have been shown. A comparative analysis was carried out for systems based on conventional spray chambers.

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Mathematical modelling of nickel behaviour in the liquid steel flowed through the one strand tundish

Cwudziński A., Jowsa J.

Archives of Materials Science and Engineering

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2012

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Vol. 57, nr 2

63--68

EN

Purpose: The continuous steel casting (CSC) technology is a dynamically developing method for obtaining steel semi-finished product in the form of a continuous casting slabs, blooms and billets. During the course of the CSC process, the liquid form of steel offers a possibility of introducing alloy additions to adjust the chemical composition or modify the non-metallic inclusions. The aim of the tests was to verify the degree of chemical homogenization of the steel after the addition of nickel. Design/methodology/approach:The device under examination is a wedge-shaped single-nozzle tundish of a capacity of 30 Mg. Computer simulation of the liquid steel flow and alloy addition behaviour in turbulent motion conditions was done using the Ansys-Fluent® computer program. Due to the complexity of alloy addition dissolution and dispersion in metallurgical processes, a decision was made to use the Species Model available within the Ansys-Fluent® program. Findings: The computer simulation produced a picture of the flow of liquid steel and the spread of nickel within the liquid steel volume. To illustrate the chemical homogenization process spatially and in a greater detail, the Ni diffusion process was monitored at selected measurement points situated in the tundish working space region. Research limitations/implications: Numerical model not include melting process of alloy addition. Practical implications: The results from numerical simulation could be use to elaborate a method of controlled alloy addition feeding to the liquid steel during continuous steel casting process. Originality/value:The paper present results of alloy addition mixing process in the liquid steel flowed through the continuous casting slab tundish.

3

On Dynamic Interaction Between the Runway and the Aircraft Landing-Gear Using the Analytical Approach

Szolc T.

Machine Dynamics Problems

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2006

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Vol. 30, No. 1

73-95

EN

High static and dynamic overloads caused by the aircraft landing gears moving on the airport runways are a source of uncontrolled cracking of the runway upper layers. In order to investigate this problem the proper analytical model of the runway under moving load is proposed. The finite distance of the runway upper layer is represented by the rectangular continuous Kirchhoff's plate resting on the visco-elastic foundation playing a role of dynamic interface with the runway supporting layer. The plate heterogeneity caused by the runway transverse notches has been taken into consideration in the form of fictitious external response-dependent elastic bending moments. The initial deflections of the runway upper layer due to thermal forces are induced in the model by the equivalent mechanical loads imposed to the plate. Excitation of the plate due to the aircraft landing-gear is represented by the set of moving non-inertial forces, mutual spacing and number of which correspond respectively to the structure and the total number of wheels of the real landing-gear of the assumed aircraft. Numerical simulation of dynamic interaction between the runway and the aircraft landing-gear has been performed by means of the modal approach for various running speeds of the heavy aircraft. The quantities of interests are the dynamic transverse deflections of the plate as well as the normal stress in the notch cross-sections.