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Study of velocity field in crossroads areas
Kellnerová, Radka ; Jaňour, Zbyněk
The aim of this project is to study the influence of boundary conditions on contaminant spreading in a urban area model. The urban area model was composed of simple elements shapes of crossroads: X-shaped, T-shaped and skew intersection. The project at the beginning - by now only results for T-shaped crossroads are available. The experiment took place in an environmental aerodynamics tunnel IT AS CR in Nový Knín. First results show accumulation of high values of Reynolds stress above the area of crossroads center, whereas the velocity field is weaker when compared with more remote area. In specific distance from the intersection the recirculating zone appears. With increasing distance from intersection the center of zone moves counter main flow and up.
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Proudění a rozptyl zněčištění v idealizované městské zástavbě
Šeděnková, Hana ; Jaňour, Zbyněk
The aim of the experiment was a measurement of the flow in the urban canopy layer - the portion of boundary layer of atmosphere between the roof tops and the ground. The work took place in the boundary layer wind tunnel. The Laser Doppler Anemometry was used as a flow measurement technique. The simplified model of the urban build-area (regularly placed cubes on the ground) was put into the tunnel. The big influence of the model on the flow was found.
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Modelování úniku a disperze nebezpečného plynu
Jaňour, Zbyněk ; Bezpalcová, Klára ; Erhart, Jakub ; Kellnerová, Radka ; Šeděnková, Hana
Liquefied industrial gases and liquefied energy gases are transported, stored and used in steadily increasing amounts.Since the vapours of many of these chemicals are either toxic or flammable or both, there is heightened concern amongst public and regulatory bodies on potential hazards in a case of accidental releases. The objective of this contribution is to present the concept and result of a wind tunnel study of the dispersion of pollution clouds in a atmospheric boundary layer. Scaling laws, which have to be fulfilled in order to ensure model/prototype similitary, have been developed. Examples of the method application have been demonstrated.
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Měření proudění v městském baldachýnu
Šeděnková, Hana ; Jaňour, Zbyněk
The aim of the experiment was a measurement of the flow in the urban canopy layer - the portion of boundary layer of atmosphere between the roof tops and the ground.The work took place in thwe boundary layer wind tunnel. The Laser Doppler Anemometry was used as a flow measurement technique. The simplifed model of the urban build-up area (regularly placed cubes on the ground) was put into the tunnel. The big influence of the model on the flow was found.
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Wind tunnel concentration field study in a urban area
Jaňour, Zbyněk ; Kellnerová, Radka ; Bezpalcová, Klára
The aim of the project was to study the influence of boundary conditions on contaminant spreading in a urban area model. The experiment was conducted a low-speed open-circuit tunnel. The urban area model was scaled down to 1:200. The model aimed to simulate a typical street with intense traffic, in our case specifically the Podbielski Strasse in Hannover (Germany). The downstreet flow was at an aproximate angle of 45 degrees to the street axis. Traffic was simulated by a double-line source. In the course of the experiment we have replaced a convoluted model of a park in the upstream area with simpler elements of varying size and density. We then compared the concentration field of the new arrangement with the original concentration field. All configurations led to a decrease of concentration . In ares where the original concentration had reached the highest values, the most significant decrease was obtained.
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Pollutant diffusion in the idealized build-up area
Šeděnková, Hana ; Jaňour, Zbyněk ; Leitl, B.
The essence of the problem consist in the way of pollutant diffusion in the urban build-up area. The measurement of the concentration field of the emission from the point (chimney) and line (street) source in the model of the idealized urban build-up area was done in the boundary layer wind tunnel. Dependence on the location of this source against model and also dependence on the geometric setting of the model (both density of buildings and location of street canyons) was found.
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