Geysering Generated by Large Air Pockets Released through Water-Filled Ventilation Shafts

Vasconcelos, José G.; Wright, Steven J.

doi:10.1061/(asce)hy.1943-7900.0000332

Cited by 79 publications

(39 citation statements)

References 11 publications

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“…Although experiments of the type presented in this chapter have been conducted in the past by Lewis (2011) and Vasconcelos and Wright (2011), they have primarily concentrated on the behavior of relatively large air pocket volumes. Also the experiments by Vasconcelos and Wright were all performed with a riser height of 0.61 m and could only observe that for large vertical surges the water spilled out the top of the riser.…”

Section: Discussionmentioning

confidence: 99%

“…Vasconcelos and Wright (2006) have suggested a number of mechanisms by which a rapidly filling pipeline could create trapped air pockets. Vasconcelos and Wright (2011) and Lewis (2011) have presented the results of small scale laboratory experiments that suggest that geysers occur as an entrapped pocket of air, migrating along the crown of a nearly horizontal surcharged tunnel, reaches a vertical riser; the rising air forces the water up ahead of it as it is expelled. The laboratory experiments do not reproduce all the phenomena observed in large scale systems and the differences are attributed to scale effects in the small scale experiments.…”

Section: Introductionmentioning

confidence: 99%

“…Wright et al (2011) present the results of video and pressure measurements at a riser in a stormwater tunnel in Minneapolis, Minnesota to argue that the observations are consistent with the release of discrete air pockets and not surge in the liquid phase. Vasconcelos and Wright (2011) presented a numerical modeling framework that could reproduce the essential features of both the free surface rise of the surcharged water in the vertical riser and the rise of the air bubble displacing the water. The study indicated the important influence of the riser diameter relative to the tunnel diameter, with larger vertical water displacement associated with smaller riser diameters.…”

Section: Introductionmentioning

confidence: 99%

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Influence of Air Pocket Volume on Manhole Surge

Wright

2013

JWMM

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Large discrete air pockets trapped along the crown of a nearly horizontal stormwater tunnel have been shown in laboratory experiments to produce large vertical surges of water as the air is expelled through a vertical riser connected to the tunnel crown. The phenomenon has been hypothesized as the source of observed geysers from manholes in such systems. A previous theoretical framework that assumes an unlimited supply of air has been shown to reproduce the essential details of laboratory experiments although deviations were observed in tests with smaller air volumes. However, it is clear that if the air volume is sufficiently small, reduced surges must occur. Previous experiments also indicate that riser diameter is a significant parameter with smaller diameters resulting in larger surges.Experiments were conducted in which the air pocket volume and riser diameter were systematically varied. Vertical surges (when normalized by the tunnel diameter) from ~0.2 to >25 were observed, confirming that larger surges were associated with larger air pocket volumes and smaller riser diameters. Both variables have significant influence on the observed surge. The experiments suggest that a minimum air pocket volume when normalized by the cube of the tunnel diameter is necessary in order to attain the maximum surge levels.In addition, the experiments recorded transient pressures near the base of the riser. These pressure traces showed significant similarity to pressures recorded during geyser events in a large stormwater tunnel, which gives support to previous arguments that geysers observed from manholes in stormwater tunnels are associated with the release of discrete pockets of trapped air.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of Air Pocket Volume on Manhole Surge

Wright

2013

JWMM

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“…Yet evidence presented by Wright et al (2011) of field pressure measurements during an actual geyser episode shows that such episodes occurred even when the HGL was far below the grade. Also, experimental work by Vasconcelos and Wright (2011) has proven that the release of large air pockets through water-filled ventilation towers may lead to geysering, and the likelihood of such events increases significantly for smaller diameter ventilation towers.…”

Section: Introductionmentioning

confidence: 99%

Kinematics of Entrapped Air Pockets Within Stormwater Storage Tunnels

Chosie

Vasconcelos

2013

JWMM

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During the rapid filling of stormwater storage tunnels, which is anticipated to occur during intense rain events, a number of different mechanisms may lead to the entrapment of air pockets, as described by Vasconcelos and Wright (2006). Entrapped air pockets have been linked to operational issues such as damaging surges, loss of storage capacity and severe geysering upon their release through water filled vertical shafts. However, the mechanisms behind the motion of these finite volume pockets following their entrapment still require further investigation.For discrete air pockets (as opposed to stratified air-water flow conditions) a balance between drag and buoyancy is expected to control the motion of large pockets in closed conduits. Previous related investigations approached the problem of pocket motion in the context of water mains, focusing on the determination of a minimum velocity to ensure air pocket removal. In the context of the rapid filling of stormwater tunnels, water flows cannot be pre-specified, and the pocket celerity thus becomes an important parameter, particularly in the context of numerical simulation for such flows.This chapter presents the preliminary results of an experimental investigation performed at Auburn University in which different air pocket volumes are released in pressurized closed pipe flow at selected slopes and flow rates. The kinematics of air pockets are studied for various flow conditions with the goal of obtaining a better understanding between observed pocket celerity and its relation to pocket volume, flow velocity and pipeline slope.

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“…Wright et al (2007) and Vasconcelos and Wright (2011) discuss the results of laboratory experiments in which an air pocket arriving at a vertical riser forces water standing in the riser to be propelled upwards. Lewis et al (2011) and Wright et al (2011) present the results of field measurements in a stormwater tunnel and conclude that the release of entrapped air must be responsible for the formation of observed geysers through a large diameter manhole.…”

mentioning

confidence: 99%