Drag reduction in boiling Taylor-Couette turbulence

Rodrigo Ezeta, Dennis Bakhuis, Sander G. Huisman, Chao Sun, Detlef Lohse*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

We create a highly controlled laboratory environment - accessible to both global and local monitoring - to analyse turbulent boiling flows and in particular their shear stress in a statistically stationary state. By precisely monitoring the drag of strongly turbulent Taylor-Couette flow (the flow in between two coaxially rotating cylinders, Reynolds number) during its transition from non-boiling to boiling, we show that the intuitive expectation, namely that a few volume per cent of vapour bubbles would correspondingly change the global drag by a few per cent, is wrong. Rather, we find that for these conditions a dramatic global drag reduction of up to 45 % occurs. We connect this global result to our local observations, showing that for major drag reduction the vapour bubble deformability is crucial, corresponding to Weber numbers larger than one. We compare our findings with those for turbulent flows with gas bubbles, which obey very different physics from those of vapour bubbles. Nonetheless, we find remarkable similarities and explain these.

Original languageEnglish
Pages (from-to)104-118
Number of pages15
JournalJournal of fluid mechanics
Volume881
DOIs
Publication statusPublished - 25 Dec 2019

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drag reduction
Drag reduction
boiling
Boiling liquids
Turbulence
bubbles
turbulence
Vapors
Drag
vapors
drag
Monitoring
Formability
rotating cylinders
Turbulent flow
Shear stress
Couette flow
Reynolds number
Physics
turbulent flow

Keywords

  • boiling
  • drag reduction
  • rotating turbulence

Cite this

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title = "Drag reduction in boiling Taylor-Couette turbulence",
abstract = "We create a highly controlled laboratory environment - accessible to both global and local monitoring - to analyse turbulent boiling flows and in particular their shear stress in a statistically stationary state. By precisely monitoring the drag of strongly turbulent Taylor-Couette flow (the flow in between two coaxially rotating cylinders, Reynolds number) during its transition from non-boiling to boiling, we show that the intuitive expectation, namely that a few volume per cent of vapour bubbles would correspondingly change the global drag by a few per cent, is wrong. Rather, we find that for these conditions a dramatic global drag reduction of up to 45 {\%} occurs. We connect this global result to our local observations, showing that for major drag reduction the vapour bubble deformability is crucial, corresponding to Weber numbers larger than one. We compare our findings with those for turbulent flows with gas bubbles, which obey very different physics from those of vapour bubbles. Nonetheless, we find remarkable similarities and explain these.",
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Drag reduction in boiling Taylor-Couette turbulence. / Ezeta, Rodrigo; Bakhuis, Dennis; Huisman, Sander G.; Sun, Chao; Lohse, Detlef.

In: Journal of fluid mechanics, Vol. 881, 25.12.2019, p. 104-118.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Drag reduction in boiling Taylor-Couette turbulence

AU - Ezeta, Rodrigo

AU - Bakhuis, Dennis

AU - Huisman, Sander G.

AU - Sun, Chao

AU - Lohse, Detlef

PY - 2019/12/25

Y1 - 2019/12/25

N2 - We create a highly controlled laboratory environment - accessible to both global and local monitoring - to analyse turbulent boiling flows and in particular their shear stress in a statistically stationary state. By precisely monitoring the drag of strongly turbulent Taylor-Couette flow (the flow in between two coaxially rotating cylinders, Reynolds number) during its transition from non-boiling to boiling, we show that the intuitive expectation, namely that a few volume per cent of vapour bubbles would correspondingly change the global drag by a few per cent, is wrong. Rather, we find that for these conditions a dramatic global drag reduction of up to 45 % occurs. We connect this global result to our local observations, showing that for major drag reduction the vapour bubble deformability is crucial, corresponding to Weber numbers larger than one. We compare our findings with those for turbulent flows with gas bubbles, which obey very different physics from those of vapour bubbles. Nonetheless, we find remarkable similarities and explain these.

AB - We create a highly controlled laboratory environment - accessible to both global and local monitoring - to analyse turbulent boiling flows and in particular their shear stress in a statistically stationary state. By precisely monitoring the drag of strongly turbulent Taylor-Couette flow (the flow in between two coaxially rotating cylinders, Reynolds number) during its transition from non-boiling to boiling, we show that the intuitive expectation, namely that a few volume per cent of vapour bubbles would correspondingly change the global drag by a few per cent, is wrong. Rather, we find that for these conditions a dramatic global drag reduction of up to 45 % occurs. We connect this global result to our local observations, showing that for major drag reduction the vapour bubble deformability is crucial, corresponding to Weber numbers larger than one. We compare our findings with those for turbulent flows with gas bubbles, which obey very different physics from those of vapour bubbles. Nonetheless, we find remarkable similarities and explain these.

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