Experimental investigation of vortex ring formation as a consequence of spiral vortex re-connection

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61388998%3A_____%2F19%3A00571285" target="_blank" >RIV/61388998:_____/19:00571285 - isvavai.cz</a>

Výsledek na webu

<a href="https://iopscience.iop.org/article/10.1088/1755-1315/405/1/012033/pdf" target="_blank" >https://iopscience.iop.org/article/10.1088/1755-1315/405/1/012033/pdf</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1088/1755-1315/405/1/012033" target="_blank" >10.1088/1755-1315/405/1/012033</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Experimental investigation of vortex ring formation as a consequence of spiral vortex re-connection

Popis výsledku v původním jazyce

The unsteady shape variation of a cavitating spiral vortex is experimentally studied pointing out the repetitive creation of vortex ring (or vortex loop). To generate the spiral vortex structure, a newly designed vortex generator is employed. This generator is used to study the decelerated swirling flow leading to the spiral vortex formation as a consequence of spiral vortex breakdown, which is considered to be the main triggering mechanism for the occurrence of the coherent vortex rope structure in the Francis turbine draft tube operated at part load conditions. Thanks to its design, the vortex generator enables to change the ratio between fluxes of axial momentum and tangential moment of momentum of generated swirl. Using this set-up, the behavior of the vortex structure changes in a similar way as the flow rate variation in the draft tube of Francis turbine. At certain flow conditions, the spiral vortex movement is characterized by sudden spiral entanglement leading to disconnection of a vortex ring and followed by spiral reconnection. Thanks to the transparent diffuser of the swirl generator apparatus, both high-speed camera recording of the cavitating vortex and PIV measurements of velocity fields at cavitationfree conditions are employed. The main aim of this paper is to link the visual observation of the above described vortex dynamics with the velocity fields measured in one longitudinal and one cross-sectional planes.

Název v anglickém jazyce

Experimental investigation of vortex ring formation as a consequence of spiral vortex re-connection

Popis výsledku anglicky

The unsteady shape variation of a cavitating spiral vortex is experimentally studied pointing out the repetitive creation of vortex ring (or vortex loop). To generate the spiral vortex structure, a newly designed vortex generator is employed. This generator is used to study the decelerated swirling flow leading to the spiral vortex formation as a consequence of spiral vortex breakdown, which is considered to be the main triggering mechanism for the occurrence of the coherent vortex rope structure in the Francis turbine draft tube operated at part load conditions. Thanks to its design, the vortex generator enables to change the ratio between fluxes of axial momentum and tangential moment of momentum of generated swirl. Using this set-up, the behavior of the vortex structure changes in a similar way as the flow rate variation in the draft tube of Francis turbine. At certain flow conditions, the spiral vortex movement is characterized by sudden spiral entanglement leading to disconnection of a vortex ring and followed by spiral reconnection. Thanks to the transparent diffuser of the swirl generator apparatus, both high-speed camera recording of the cavitating vortex and PIV measurements of velocity fields at cavitationfree conditions are employed. The main aim of this paper is to link the visual observation of the above described vortex dynamics with the velocity fields measured in one longitudinal and one cross-sectional planes.

Druh

D - Stať ve sborníku

CEP obor

—

OECD FORD obor

20302 - Applied mechanics

Projekt

<a href="/cs/project/GA17-01088S" target="_blank" >GA17-01088S: Prostorová nestabilita smykové vrstvy při nepříznivém gradientu tlaku</a><br>

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2019

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název statě ve sborníku

IOP Conference Series: Earth and Environmental Science

ISBN

—

ISSN

1755-1307

e-ISSN

—

Počet stran výsledku

6

Strana od-do

012033

Název nakladatele

Universite Stuttgart

Místo vydání

Stuttgart

Místo konání akce

Stuttgart

Datum konání akce

9. 10. 2019

Typ akce podle státní příslušnosti

WRD - Celosvětová akce

Kód UT WoS článku

000562376700033