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Energy dissipation through entrained air compression in plunging jets

Energy dissipation through entrained air compression in plunging jets
Energy dissipation through entrained air compression in plunging jets
The energy dissipation in plunge pools is often related to air entrainment in the plunging jet. Recent experimental work showed that the void fractions
below the impinging jet are significantly smaller than outside the jet impact. This was attributed to the compression of the entrained air bubbles. In
this paper, the thermodynamics of air bubble compression is introduced as a novel energy dissipation mechanism in civil engineering hydraulics.
For the analysis of reported experimental data, isothermal conditions were applied as a lower bound approximation. It was found that the energy
dissipation rates range from 2.7–9.7% for a jet velocity of 10ms−2 and void fractions of 0.11 and 0.31, to 15.9–36.0% for a jet velocity of 24.5ms−1
and void fractions of 0.35–0.55. The results may explain the difference between energy dissipation rates in plunge pools at model and full scale.
Aerated flow; bubble dynamics; energy dissipation; multiphase flow; similarity (scaling) theory
0022-1686
1
Muller, Gerald
f1a988fc-3bde-429e-83e2-041e9792bfd9
Muller, Gerald
f1a988fc-3bde-429e-83e2-041e9792bfd9

Muller, Gerald (2019) Energy dissipation through entrained air compression in plunging jets. Journal of Hydraulic Research, 1. (doi:10.1080/00221686.2019.1609105).

Record type: Article

Abstract

The energy dissipation in plunge pools is often related to air entrainment in the plunging jet. Recent experimental work showed that the void fractions
below the impinging jet are significantly smaller than outside the jet impact. This was attributed to the compression of the entrained air bubbles. In
this paper, the thermodynamics of air bubble compression is introduced as a novel energy dissipation mechanism in civil engineering hydraulics.
For the analysis of reported experimental data, isothermal conditions were applied as a lower bound approximation. It was found that the energy
dissipation rates range from 2.7–9.7% for a jet velocity of 10ms−2 and void fractions of 0.11 and 0.31, to 15.9–36.0% for a jet velocity of 24.5ms−1
and void fractions of 0.35–0.55. The results may explain the difference between energy dissipation rates in plunge pools at model and full scale.

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More information

Accepted/In Press date: 15 April 2019
Published date: 29 May 2019
Keywords: Aerated flow; bubble dynamics; energy dissipation; multiphase flow; similarity (scaling) theory

Identifiers

Local EPrints ID: 431643
URI: http://eprints.soton.ac.uk/id/eprint/431643
ISSN: 0022-1686
PURE UUID: 7f937918-8cc7-4813-8d1f-ed6213da595f

Catalogue record

Date deposited: 11 Jun 2019 16:30
Last modified: 07 Oct 2020 06:16

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