Publication detail
Connection between inlet velocity field and diffuser flow instability
RUDOLF, P.
Czech title
Spojitost mezi vstupním rychlostním polem a nestabilitou proudění v difuzoru
English title
Connection between inlet velocity field and diffuser flow instability
Type
journal article - other
Language
en
Original abstract
Simulations of the flow in a straight diffuser were carried out for different inlet velocity profiles equivalent to the real turbine operating points. Frequencies and magnitudes of pressure pulsations of the rotating vortex rope were recorded. Two types of vortices were detected. The first one is a thin vortex with higher frequency and relatively low pressure amplitudes corresponding to higher part load turbine operation. For lower loads, further from best efficiency point, a huge vortex rotating on higher diameter appears, which is accompanied by massive pressure pulsations, but with lower frequency. Connections of these two regimes with inlet circumferential velocity com-ponent are discussed in the paper.
Czech abstract
Byly provedeny simulace proudění v přímém difuzoru se vstupními rychlostními profily odpovídajícími skutečné Francisově turbíně. Výsledky ukázaly na dva rozdílné typy vírových struktur. První je tenký vír s vyšší frekvencí a relativně nízkými amlitudami tlaku. Tento vír se objevuje pro vyšší částečné zatížení turbíny. Pro nižší průtoky, dále od optimálního bodu, se objevuje masívní vír doprovázený výraznými pulzacemi tlaku. Frekvence jeho rotace je ovšem nižší. Článek dává do souvislosti různá vstupní rychlostní pole se vznikem rpzdílného charakteru vírových struktur.
English abstract
Simulations of the flow in a straight diffuser were carried out for different inlet velocity profiles equivalent to the real turbine operating points. Frequencies and magnitudes of pressure pulsations of the rotating vortex rope were recorded. Two types of vortices were detected. The first one is a thin vortex with higher frequency and relatively low pressure amplitudes corresponding to higher part load turbine operation. For lower loads, further from best efficiency point, a huge vortex rotating on higher diameter appears, which is accompanied by massive pressure pulsations, but with lower frequency. Connections of these two regimes with inlet circumferential velocity com-ponent are discussed in the paper.
Keywords in Czech
nestability, difuzor, vírový cop, vodní turbína
Keywords in English
instability, diffuser, vortex rope, hydraulic turbine
RIV year
2009
Released
01.06.2009
Publisher
University of West Bohemia
Location
Plzeň
ISSN
1802-680X
Journal
Applied andComputational Mechanics
Volume
3
Number
1
Pages from–to
177–184
Pages count
8
BIBTEX
@article{BUT47117,
author="Pavel {Rudolf},
title="Connection between inlet velocity field and diffuser flow instability",
journal="Applied andComputational Mechanics",
year="2009",
volume="3",
number="1",
month="June",
pages="177--184",
publisher="University of West Bohemia",
address="Plzeň",
issn="1802-680X"
}