Measurements of Bubble Rise Characteristics in Various Temperatures and Liquid Velocities

2002 ◽  
Author(s):  
Kazuhiro Torimoto ◽  
Masanori Nishiura ◽  
Tomoe Tanaka ◽  
Tomio Okawa ◽  
Isao Kataoka
Keyword(s):  
Turbulent Flow ◽  
Nuclear Reactor ◽  
Liquid Velocity ◽  
Bubbly Flow ◽  
Measured Data ◽  
Rise Velocity ◽  
Reactor Safety ◽  
Bubble Rise ◽  
Bubble Rise Velocity ◽  
Nuclear Reactor Safety

Single bubble rise characteristics in turbulent flow in a vertical circular pipe were experimentally observed. As a result, it was found that bubble rise velocity relative to the time averaged local liquid velocity decreases with the increase of liquid flowrate and that it also decreases with the decrease of the distance between a bubble and wall. Investigating the mechanisms of the reductions of relative velocity, new correlations were developed for accurately evaluating the bubble rise velocities in turbulent flow. Since the predicted bubble rise velocities reasonably agreed with the measured data, the new correlations could contribute to the improvement of bubbly flow calculations in nuclear reactor safety analysis.

An Analytical Study of Turbulent Dispersion of Bubbles

2001 ◽  
Author(s):  
Anthony L. Lawson ◽  
Ramkumar N. Parthasarathy
Keyword(s):  
Root Mean Square ◽  
Time Scale ◽  
Liquid Velocity ◽  
Added Mass ◽  
Mean Square ◽  
Rise Velocity ◽  
Velocity Fluctuations ◽  
Bubble Rise ◽  
Integral Time Scale ◽  
Bubble Rise Velocity

Abstract An analysis of the dispersion of bubbles in homogenous and isotropic turbulent liquid flows was performed to study the effects of bubble and flow characteristics on their dispersion. Bubbles were assumed to be spherical and to follow the fluid motion in the mean. No mass transfer occurred between the bubble and liquid; also, there was no interaction between individual bubbles. It was found that for accurate prediction of bubble dispersion requires a simultaneous consideration of the inertia of the added mass of liquid (because the inertia of the bubble itself is small) and the bubble rise velocity. Normalized bubble diffusivity, root-mean-square fluctuating velocity, and Lagrangian integral time scale were related to two non-dimensional parameters: ratio of the added mass response time to the liquid flow integral time scale, and the ratio of the bubble rise velocity to the root-mean-square liquid velocity fluctuation. In general, the bubble Lagrangian velocity auto-correlations decreased as the rise velocity ratio increased. The dependence of the autocorrelations on the time-scale ratio was complex. A surprising result was that the bubble velocity fluctuations could exceed the liquid velocity fluctuations for certain conditions because of their low inertia.

scholarly journals Nuclear reactor safety: Super-Sara's fate undecided

Nature ◽  
1982 ◽  
Vol 300 (5894) ◽  
pp. 677-677
Author(s):  
Jasper Becker
Keyword(s):  
Nuclear Reactor ◽  
Reactor Safety ◽  
Nuclear Reactor Safety
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