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Application of an anemometric hot-wire probe to the measurement of a velocity field downstream of an automotive ventilation outlet
Šíp, Jan ; Tuhovčák, Ján (referee) ; Lízal, František (advisor)
This diploma thesis deals with the research of the flow in front of the benchmark automotive vent. Using thermoanemometry, the velocity field in the area in front of the vent was measured in detail and the intensity of the turbulence was calculated. Computational fluid dynamics of the air flow from the vent was also performed using the STAR-CCM + program. In addition, the influence of the surrounding surfaces simulating the real environment of the automobile on the air flow from the vent was investigated. The diploma thesis contains the calculation of measurement uncertainty. The purpose of this thesis is to obtain complex data on the velocity field and to use them for validation of Computational fluid dynamics.
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Automotive ventilation system - comparison of an influence of boundary conditions on flow from various types of ventilation outlets
Brdečko, Radim ; Pokorný, Jan (referee) ; Lízal, František (advisor)
Diploma thesis deals with a research of the flow in front of three different automotive vents. The velocity field and intensity of the turbulence was measured in detail, using thermoanemometry. After that the same data was measured with PIV method and validation was performed. The difference between achieved data was investigated. The design among the vents was also investigated, because it’s fundamentally affects the air flow. The purpose of this thesis is to obtain data about the velocity field using two methods and their subsequent use to validate numerical simulations, which will be performed in the future. The diploma thesis also contains the calculation of measurement uncertainty.
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Measurement of the velocity distribution in a low-velocity outlet jet
Uhlář, Václav ; Pavelek, Milan (referee) ; Janotková, Eva (advisor)
Diploma thesis deal with measuring air-jet generated by low-velocity outlet. Diploma thesis piles of several part. First part includes velocity measurment (flow volumes) single ventilators. Follows measuring velocity distribution in air-jet generated by low-velocity outlet, his vizualization by the smoke method. Last point is problems errors and uncertainties measuring. Thesis likewise includes appendices, where there are mentioned tables from single maesuring and setting frequency transducers.
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Measurements of velocity in the channel bottom boundary layer, using Particle Image Velocimetry
Vrubel, Jan ; Haluza,, Miloslav (referee) ; Zubík, Pavel (advisor)
The theme of this thesis is continue on examining relatively commonly used measurement flow field metods, which assessing the variables flows at a high level. Thesis follow up mainly the flow field in the channel bottom boundary-layer and its depending on different factors. To calculate velocity in boundary-layer is common used extrapolation method, because this boundary layer is only the small part of measuring cross section. Increase the accuracy of measurement of flow variables make the flow in the boundary layer also important. Thesis is a summary of a basic theory of flow field, but mainly is about dependent local flow velocity on position, and about deformation of flow field in boundary layer. The aim thesis is description different calculation methods of flow flow field in boundary layer and comparison to with real condition which was measured in laboratory UVS-LVV. Real condition flow field in channel bottom boundary layer is based on exact method Particle image velocimetry. The measurement results serve to compare commonly used calculation methods or different theories velocity in the channel bottom boundary layer. Outputs this thesis offers comparison, confirmation or specification calculation methods according to the results. It has been suggested several limitations on certain methods of calculation, or coefficient were modified or alternative has been proposed to calculate them.
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Lateral recirculation zones of flow in approach channel of weir
Korálová, Nikola ; Pařílková, Jana (referee) ; Zachoval, Zbyněk (advisor)
The bachelor’s thesis is divided in to the literary research and practical part. The content of the literary research is the issue of side contracted weirs, where occurs side contracted flow. The sudden change of the channel width and formation of upstream wake have direct influence on value of discharge coefficient. There are described types of the weirs, ways of computing discharge and discharge coefficients which are influenced by contraction. In the practical part of thesis is described measurement of the velocity field of side contracted flow by UVP Monitor, follow up by assessment of boundary of the upstream wake, which is situated in the approach channel in front of the weir.
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Comparison of speed measurement by hydrometric propeller and laser anemometer
Kosík, Ondřej ; Haluza,, Miloslav (referee) ; Zubík, Pavel (advisor)
This final thesis deals primarily with the comparison of two calibration approaches. It determines the degree of mutual agreement and tries to answer the reasons of their deviations. This agreement was measured by the LDA method. It was found that the calibration approach based on the reference framework of values of the previous bachelor thesis differs systematically from the calibration using calibration equations obtained from certified laboratories by -2 %. The causes of this deviation were investigated using LDA and PIV. Although a significant number of measurements were performed, all tested hypotheses were refuted and therefore it was not possible to determine their cause.
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Research of Systems for Providing the Quality of the Environment in the Car Cabin
Šíp, Jan ; Kavička, František (referee) ; Volavý, Jaroslav (referee) ; Lízal, František (advisor)
Optimal conditions of indoor environmental quality, especially thermal comfort and indoor air quality, are important because they lead to the active safety of passengers. Long-term exposure to inconvenient temperatures may cause thermal stress and negatively affects the driver’s cognitive functions. These include important abilities of drivers, such as concentration, vigilance, speed of decision-making and others. The inappropriate temperature in the cabin is one of the most dangerous factors causing car crashes. Air indoor quality is negatively affected by exhaust gases or particles from tire wear, which enter the car cabin during ventilation. This can be prevented by using an air recirculation system which does not supply outside air, but it is a closed circuit. This mode, however, causes high CO2 concentration in the cabin which can lead to excessive fatigue. This thesis deals with the influence of different ventilation systems on indoor environmental quality, i. e. thermal comfort and indoor air quality. A partial factor of thermal comfort is the flow field which was investigated downstream of a benchmark automotive vent. CFD was applied to determine the flow field downstream of a vent. The results were validated by experimental data acquired by Constant Temperature Anemometry. CFD has been also used for the evaluation of the thermal comfort of three novel ventilation systems (mixing, ceiling and floor ventilation). The results were validated by experimental data acquired by thermal manikin and climate chamber. Indoor air quality has been evaluated based on the Age of Air. The analytical empirical equation by Rajaratnam can be successfully used also to determine the throw of the jet, which is favorable, especially in light of the fact that both computational methods were not very accurate in velocity decay predictions. The Large Eddy Simulation and Reynolds-averaged Navier–Stokes method are suitable for evaluating the flow field downstream of the automotive vent. The diagrams of comfort zones were evaluated for all regimes based on equivalent temperatures. The best performance in terms of the highest level of human comfort was achieved by the ceiling ventilation in the summer conditions and by the floor ventilation in the winter conditions. From the point of view of the Age of Air, the ceiling air ventilation system is the most suitable for the winter conditions. In the summer conditions the Age of Air values for individual air ventilation concepts are very similar for both interior types.
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Comparison of speed measurement by hydrometric propeller and laser anemometer
Kosík, Ondřej ; Haluza,, Miloslav (referee) ; Zubík, Pavel (advisor)
This final thesis deals primarily with the comparison of two calibration approaches. It determines the degree of mutual agreement and tries to answer the reasons of their deviations. This agreement was measured by the LDA method. It was found that the calibration approach based on the reference framework of values of the previous bachelor thesis differs systematically from the calibration using calibration equations obtained from certified laboratories by -2 %. The causes of this deviation were investigated using LDA and PIV. Although a significant number of measurements were performed, all tested hypotheses were refuted and therefore it was not possible to determine their cause.
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