Calculation of the temperature distribution by volume inside the ski facility ‘Snezhcom’ and within the external cover of the construction in July in Moscow
1. Specification of the object
The general view of the All-season Ski Center 'Snezhcom' and its structural drawing are displayed in fig. 1-3.
Fig. 1
Fig. 2
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The external coating is produced from metal plates. The rectangular outline of the piste is produced from insulated panels of the type 'sandwich'. The areas between the outer plates and filler structures of the outline doesn't have a heating system.
For the filler structures of the refrigerated room the insulated panels of the type 'sandwich' are used. The ceiling 'sandwich panels' are designed to bear their own loads and wind loads during the installation.
2. The matter, the goal and the methods of expert computations
The aim of the expert computations were the fields of temperature distribution by volume inside the ski facility 'Snezhcom' (internal outline) and inside the external cover of the construction (external outline) in the middle of July in Moscow.
The task was to create a solid model of the skiing flank, a finite volume grid model and perform preliminary computations to obtain pressure fields, termeratures and velocities.
The solid model of the calculation area pf the skiing flank including the internal outline of a rectangular cutout and the external outline (the plate roof of the elliptical cutout with a side bar) exclusively of the presence of openings berween them as well as the fixing braces between the roof and the ceiling of the internal outline has been generated in the SolidWorks 2007 package environment. The generation of the internal and the external outlines has been performed in an independent way. The solid model of the calculation area of the internal outline has been generated by the extension of the generated cross-sectional area in three directions (two plateaus in the beginning and in the end of the flank and the flank itself) (fig. 4).
Fig. 4. The solid model of the computation area of the internal outline
The generation process of the solid model of the external outline calculation area has been divided into two stages. On the first stage, a 'fully flooded' solid model of the external outline has been generated similar to the internal outline model. On the second stage, the necessary frontal cross section of the external outline has been obtained by cutting one model from the other (fig. 5).
Fig. 5. The solid model of the computation area of the external outline
In the process of generation of the finite volume grid model, several model vatiants have been created. The grid model of the calculation area has been generated in the Star-CCM+ package environment. In order to perform test calculations, models with a prismatic wall layer and without it have been generated. On the basis of the computation resources of the customer, a simplified model and determination of calculations as preliminaty, a generation of a multimillion grid model of the skiing flank appeared to be unpractical. The dimensions of the necessary grid model of the whole calculation area has been estimated in the range of 1-2 million cells. To implement it, the docking area of the internal and the external outline has been extended insignificantly. As a result, the dimensions of the finite volume grid model of the calculation area of the internal outline with the prismatic wall layer amounts to 400 000 cells, without a prismatic wall layer 200 000 cells, and the dimensions of the infinite volume grid model of the calculation area of the external outline with the prismatic wall layer amounts to 2 200 00 cells, without a prismatic wall layer 800 000 cells.
The generation of the calculation area consisted in the setting of physical environment parameters as well as the boundaty conditions on the outlines walls. Calculations have been performed for the streamline and turbulent flow patterns with account of gravitation. An ideal gas with nonuniform density has been used as an environment. The wall temperature of the internal and external outlines has been set according to the customer data (Table 1).
Table 1
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Temperature of the external plate covering (roof) |
+52°С |
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Wall temperature of the filler structures on the part of the external outline of the flank |
+32°С |
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Wall and ceiling temperature inside the rextangular outline of the flank |
-3°С |
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Temperature of the snow covering of the flank floor |
-7°С |
3. Calculation results
The internal outline of the flank and the external outline under the rood are deemed to be insular and do not intercommunicate with each other. The natural ventilation from the open air hasn't benn taken into account. All the walls of the flank outline construction has been simulated as indefinitely thin. The task has been solved in a stationary statement. Enclosure walls between the external and the internal outline of the flank are deemed to be low-conductive. The constructional bars installed in the external outline have not been simulated. As a result of calculations a stable image of the heat convection of temperature, pressure and velocity fields in different sectional areas throughout the height and the volume of the external and the internal flank outlines. The calculation results for the mentioned task statement are displayed in fig. 6-7.
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Fig. 6. The calculated pressure, velocity and temperature fields in the vertical and cross sectional areas of the external outline of the skiing flank.
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Fig. 7. The calculated pressure, velocity and temperature fields in the vertical and cross sectional areas of the internal outline of the skiing flank.
The calculations make it evident that the air pressure and temperature are changing throughout the height and the length of the skiing flank and practically not changing throughout its width. The figures also display the picture of the termal convection (in flow lines).
Moreover, instantaneous curves of the barometric pressure on the walls and the ceiling tohroughout the flank lenght for the external and the internal outlines as well as the barometric pressure difference between the two outlines in the corresponding sections (fig. 8.1 - 8.7).
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Fig. 8.1 The pressure distribution on the ceiling of the internal outline (center section) throughout the flank length to simulate the streamline and turbulent flow patterns |
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Fig. 8.2 The pressure distribution on the ceiling of the internal outline (center section) throughout the flank length to simulate the streamline and turbulent flow patterns
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Fig. 8.3 The pressure distribution on the ceiling of the internal outline (center section) throughout the flank length to simulate the streamline and turbulent flow patterns
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Fig. 8.4 The pressure distribution on the ceiling of the internal outline (center section) throughout the flank length to simulate the streamline and turbulent flow patterns |
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Fig. 8.5 The barometric pressure distribution between the ceilings of the internal and the external outlines (center section) throughout the flank length to simulate the streamline and turbulent flow patterns
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Fig. 8.6. The barometric pressure distribution between the walls of the internal and the external outlines (center section) throughout the flank length to simulate the streamline and turbulent flow patterns
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Fig. 8.7 The barometric pressure difference distribution between the walls of the internal and the external outlines (center section) throughout the flank length to simulate the streamline and turbulent flow patterns |