Energy dissipation through entrained air compression in plunging jets

Laboratory experiments were conducted to measure entrained air bubble penetration depth and dilution of a dense vertical unconfined plunging jet to evaluate its performance as an outfall to dilute brine from desalination plants as well as a means to aerate water column. Experiments involved neutrally buoyant or dense plunging jets discharging in quiescent receiving water. The density difference between effluent and receiving water, the plunging jet length (height above water surface), and the receiving water salinity were varied in the experiments. Observed penetration depth for neutrally buoyant jets was somewhat greater than previously reported, and increased modestly with jet density. Increasing density also resulted in an increasing number of fine bubbles descending together with the dense plume. These observations can help guide the design of plunging jets to mitigate anoxic conditions in the water column when brine is introduced to a receiving water body, as with seawater desalination.

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Air entrainment and associated energy dissipation in steady and unsteady plunging jets at free surface

Applied Ocean Research ◽

10.1016/j.apor.2008.03.004 ◽

2008 ◽

Vol 30 (1) ◽

pp. 37-45 ◽

Cited By ~ 6

Author(s):

Ashabul Hoque ◽

Shin-ichi Aoki

Keyword(s):

Free Surface ◽

Energy Dissipation ◽

Air Entrainment ◽

Plunging Jets

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Some Nuclear Reactor Safety Related Aspects of Plunging Jets

18th International Conference on Nuclear Engineering: Volume 4, Parts A and B ◽

10.1115/icone18-29951 ◽

2010 ◽

Author(s):

Eckhard Krepper ◽

Frank-Peter Weiss ◽

So¨ren Alt ◽

Alexander Kratzsch ◽

Stefan Renger ◽

...

Keyword(s):

Nuclear Reactor ◽

Reactor Safety ◽

Joint Research ◽

Cfd Models ◽

Safety Research ◽

Joint Research Project ◽

Plunging Jets ◽

Nuclear Reactor Safety ◽

Entrained Air ◽

The University

Plunging jets play an important role in nuclear reactor safety research. In the present paper the case of the strainer clogging issue is considered. Entrained air caused by a plunging jet has an influence of the liquid flow field and on the fibre transport in the sump. In the paper the amount of entrained air is given as an inlet boundary condition according to correlations in the literature and confirmed by own experiments. The influence of entrained air on the fibre deposition pattern at the bottom of a tank and on the mixing procedure for the case of temperature differences between jet and tank water are investigated by CFD calculations and compared to experiments. The presented work is part of a joint research project performed in cooperation between the University of Applied Science Zittau/Go¨rlitz and Forschungszentrum Dresden-Rossendorf. The project deals with the experimental investigation of particle transport phenomena in coolant flow in Zittau and the development of CFD models for its simulation in Rossendorf (Krepper et al. 2008).

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Hydraulic design of intake structures of deeply located underground tunnel systems

Water Science & Technology ◽

10.2166/wst.1999.0461 ◽

1999 ◽

Vol 39 (9) ◽

pp. 137-144 ◽

Cited By ~ 1

Author(s):

K. Toda ◽

K. Inoue

Keyword(s):

Free Surface ◽

Energy Dissipation ◽

Vortex Flow ◽

Air Entrainment ◽

Swirling Flows ◽

Underground Storage ◽

Hydraulic Design ◽

Literature Reviews ◽

Entrained Air ◽

Air Control

This paper deals with hydraulic effects of intake structures of underground storage or tunnel systems from the aspect of energy dissipation and entrained air control. First, through the literature reviews, the advantage of vortex-flow dropshaft type is confirmed. Next, with the analytical solutions of free-surface swirling flows in vertical dropshaft, the energy dissipation effects of vortex-flow dropshaft are examined and some results of practical use are obtained. Also, the relation between the dropshaft shape and air entrainment is studied and the excellent of the helicoidal-ramp dropshaft is clarified. Based on the above results, the directions of the hydraulic designs of drop structures are proposed.

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