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Boundary layer transition visualization in aerodynamic tunnel
Holík, Denis ; Trusík, Vojtěch (referee) ; Popela, Robert (advisor)
The purpose of the thesis was to propose and test an imaging method that allows visualization of the transition of a laminar boundary layer to a turbulent one and visualization of laminar boundary layer separation on the side mirror of a car. The beginning of the paper discusses the theoretical foundations associated with boundary layer formation and its evolution under various conditions. Afterwards, a survey of existing imaging methods that allow the display of flow on the surface of bodies was carried out. Of these methods, imaging using a thermal imaging camera was selected on the basis of the specified characteristics. The method using oil film (oilflow) was chosen as a control. Using both methods, experiments were conducted to confirm the suitability of the thermal imaging method for visualizing the transition of a laminar boundary layer to a turbulent boundary layer. The final test revealed the presence of laminar boundary layer separation on the upper cover of the car side mirror. At the end of the thesis, possible errors associated with the two chosen visualization methods were summarized, and ways to incorporate the thermal imaging method into automotive testing were proposed.
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Boundary layer transition visualization in aerodynamic tunnel
Holík, Denis ; Trusík, Vojtěch (referee) ; Popela, Robert (advisor)
The purpose of the thesis was to propose and test an imaging method that allows visualization of the transition of a laminar boundary layer to a turbulent one and visualization of laminar boundary layer separation on the side mirror of a car. The beginning of the paper discusses the theoretical foundations associated with boundary layer formation and its evolution under various conditions. Afterwards, a survey of existing imaging methods that allow the display of flow on the surface of bodies was carried out. Of these methods, imaging using a thermal imaging camera was selected on the basis of the specified characteristics. The method using oil film (oilflow) was chosen as a control. Using both methods, experiments were conducted to confirm the suitability of the thermal imaging method for visualizing the transition of a laminar boundary layer to a turbulent boundary layer. The final test revealed the presence of laminar boundary layer separation on the upper cover of the car side mirror. At the end of the thesis, possible errors associated with the two chosen visualization methods were summarized, and ways to incorporate the thermal imaging method into automotive testing were proposed.
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Numerická simulace Kármánovy vírové řady
Šponiar, D. ; Trávníček, Zdeněk ; Vogel, Jiří
The wake airflow behind a circular cylinder has been investigated using FLUENT solver. The flow is assumed to be two–dimensional, laminar, isothermal, and incompressible. The Reynolds number ranges Re = 30:-170. The computations give the steady wake flow for Re = 30:-60 and the periodic vortex shedding (von Kármán vortex street) for Re = 60:-170. The vortex shedding frequency has been quantified in the term of the Strouhal number–Reynolds number relationship. The present results agree very well with the previous experimental data, the maximum deviations of the simulations and experiments are within 1.2%.
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