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Study of vortical structures generated by a swirl generator
Kurková, Michaela ; Pochylý, František (referee) ; Urban, Ondřej (advisor)
This bachelor’s thesis deals with the study of vortical structures generated by a swirl generator. The theoretical part is focused on the description of experimental and numerical studies of the vortex rope phenomenon. This part also includes a brief overview of vortex identification methods. The second part is dedicated to the study of vortical structures captured by CFD simulations. The vortex identification methods are compared on an example of the vortex rope.
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Multiphase CFD simulation of spiral vortex in vaneless swirl generator
Zatloukal, Filip ; Burda, Radim (referee) ; Štefan, David (advisor)
This thesis deals with multiphase CFD simulation of spiral vortex in bladeless swirl generator. Spiral vortex formed in the draft tube of hydraulic turbine is called “vortex rope”. Vortex rope is formed when the turbine is forced to operate in off-design conditions. Assessment of swirl generators used for the study of vortex ropes is presented. The multiphase CFD simulations are carried out for the bladeless swirl generator with use of Reynolds stress turbulence model in ANSYS Fluent software. The results from calculations are compared with available experimental data previously measured on this particular swirl generator. The main focus is on detailed analysis of velocity field in the diffusor part of the generator where the vortex appears. Experimentally estimated swirl number is compared with the one evaluated from simulation. The swirl number is also monitored along the length of diffuser and downstream. Finally, the synchronous and asynchronous pressure pulsations are studies by means of Fast Fourier Transformation.
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Reduced order model of the swirling flow
Urban, Ondřej ; SUSAN-RESIGA, Romeo Florin (referee) ; Uruba, Václav (referee) ; Rudolf, Pavel (advisor)
Tato dizertační práce je zaměřená na studium vírového copu. Za tímto účelem byl navržen nový vírový generátor umožňující regulaci intenzity zavíření. Chování vírového copu bylo studováno jak numericky, tak experimentálně. Byly použity numerické simulace zachycující i část energetické kaskády turbulentního proudění, dále byly navrženy metody vizualizace dat založené na objemovém renderování a byla testována různá vírová kritéria. Také bylo studováno několik metod dekompozice proudových polí. Nakonec byly navrženy metody pro extrakci kvaziperiodických módů. S využitím těchto metod byl sestaven redukovaný model pro daný rozsah provozních bodů.
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Multiphase CFD simulation of spiral vortex in vaneless swirl generator
Zatloukal, Filip ; Burda, Radim (referee) ; Štefan, David (advisor)
This thesis deals with multiphase CFD simulation of spiral vortex in bladeless swirl generator. Spiral vortex formed in the draft tube of hydraulic turbine is called “vortex rope”. Vortex rope is formed when the turbine is forced to operate in off-design conditions. Assessment of swirl generators used for the study of vortex ropes is presented. The multiphase CFD simulations are carried out for the bladeless swirl generator with use of Reynolds stress turbulence model in ANSYS Fluent software. The results from calculations are compared with available experimental data previously measured on this particular swirl generator. The main focus is on detailed analysis of velocity field in the diffusor part of the generator where the vortex appears. Experimentally estimated swirl number is compared with the one evaluated from simulation. The swirl number is also monitored along the length of diffuser and downstream. Finally, the synchronous and asynchronous pressure pulsations are studies by means of Fast Fourier Transformation.
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Study of vortical structures generated by a swirl generator
Kurková, Michaela ; Pochylý, František (referee) ; Urban, Ondřej (advisor)
This bachelor’s thesis deals with the study of vortical structures generated by a swirl generator. The theoretical part is focused on the description of experimental and numerical studies of the vortex rope phenomenon. This part also includes a brief overview of vortex identification methods. The second part is dedicated to the study of vortical structures captured by CFD simulations. The vortex identification methods are compared on an example of the vortex rope.
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