Minimum pump submergence to prevent surface vortex formation

Werth, David; Frizzell, Carl

doi:10.3826/jhr.2009.2699

Cited by 22 publications

(7 citation statements)

References 5 publications

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“…Recently, Werth & Frizell (2009) (30) have proposed such an empirical formula for the vertical-wet-pit pump as S c / D = 2.1 + 4Fr 2/3 / 3, modifying the formula for the vertical-down-flowing intake pump by Gulliver & Rindels. Their formula shows a better approximation than the 1998 HI standard by ANSI, such as S c / D = 1 + 2.3Fr.…”

Section: Journal Of Fluid Science and Technologymentioning

confidence: 99%

Occurrence Condition of Air Entrainment into a Vertical Wet-Pit Pump

Hirata

Funaki

Kubota

et al. 2013

JFST

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In the present study, we consider the air entrainment into a suction pipe which is vertically inserted down into a suction sump across a mean free-water surface. This configuration is often referred to as the "vertical wet-pit pump", and has many practical advantages in construction, maintenance and operation. In particular, we focus our concern upon the critical submergence depth S c , which is one of the prime and conventional indicators for the air-entrainment occurrence. By a systematic approach, we experimentally investigate the influences of kinetic and geometric parameters upon S c. As the kinetic parameters, we consider the Reynolds number Re and the Weber number We, in addition to the Froude number Fr, on such a basis as Fr is not much larger than unity in many actual cases. As the geometric parameters, we consider back clearance X, sump breadth B and bottom clearance Z. Here, all parameters are non-dimensionalised by the outside diameter D and the intake velocity V i of the suction pipe. As a result, we reveal the effects of such six parameters upon S c. The We effect, namely, the surface-tension effect can be ignored at We > 12. And, the Re effect, namely, the viscous effect becomes negligibly small at Re > 3×10 4. Under such conditions for We and Re, we could consider only the Fr effect, namely, the gravitational effect. Concerning the X/D and B/D effects, S c /D attains the maximum at a certain X/D or B/D. On the other hand, the Z/D effect is monotonic, and becomes small at Z/D > 2.5. Some aspects of these geometric effects can be evaluated by a local-Froude-number effect on the basis of the global relation between S c /D and Fr. And, the other aspects is necessarily considered to be related with the flow structure in the suction sump.

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Section: Journal Of Fluid Science and Technologymentioning

confidence: 99%

Occurrence Condition of Air Entrainment into a Vertical Wet-Pit Pump

Hirata

Funaki

Kubota

et al. 2013

JFST

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“…1a3), causing hydraulic problems such as discharge reduction, vibrations, and loss of efficiency in turbines, pumps, and water-conveying structures. Extensive research has been conducted on air-entraining vortices (Anwar et al 1978, Ansar et al 2002, Werth and Frizzell 2009. Hydraulic engineers frequently discuss the effects of dimensionless parameters and the similarity conditions between model and prototype on air-entraining vortices.…”

Section: Introductionmentioning

confidence: 99%

Effects of dimensionless parameters on air-entraining vortices

Taştan

Yıldırım

2010

Journal of Hydraulic Research

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The effects of dimensionless parameters and boundary friction on air-entraining vortices and the critical submergence of an intake located in nocirculation imposed cross-flow and still water are investigated. It is found that limit values affect these vortices and the critical submergence, depending on the flow and geometrical conditions. The slower the cross-flow is, the higher these limit values are. The boundary friction effects on air-entraining vortices at intakes located in both a cross-flow and still water are also examined. The boundary section close to the free surface has a much larger effect than the boundary section away from it. The frictional effect of a boundary section on an air-entraining vortex depends on the distance between the boundary and the vortex centre at the free surface (above the intake centre). The boundary has maximum frictional effect if it is located at the vortex centre.

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“…The translation of the results obtained from a model to the full prototype scale is the main focus. Studies of the F, R, and W numbers include those by Jain et al (1978), Anwar et al (1978), Odgaard (1986), Padmanabhan and Hecker (1984), Werth and Frizzell (2009), Sarkardeh et al (2010), Trivellato (2010, Mahyari et al (2010), Felder and Chanson (2009), Heller (2011), and Pfister and Chanson (2012. These researchers have found that the critical submergences measured in the models constructed in accordance with dynamic similarity do not correspond to the critical submergences in the prototype.…”

Section: Introductionmentioning

confidence: 98%

Effects of Froude, Reynolds, and Weber numbers on an air-entraining vortex

Taştan

Yıldırım

2014

Journal of Hydraulic Research

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The present study highlights the need for using both the kinematic and dynamic similarities in scaled models of the critical submergence of vertical vortices at intake structures. A semi-theoretical approach, which is based on the principle of flow continuity, is used in combination with published experimental data. The present study shows that only the kinematic similarity is needed to model the ratio of the critical submergence to the diameter of the intake. For intakes that have an identical ratio of the intake velocity to the velocity at the critical spherical sink surface (CSSS), the ratio of the critical submergence to the diameter of the intake is identical regardless of the flow and the geometrical conditions. The new finding is that dynamic similarity is not required for the prediction of the ratio of the critical submergence to the intake diameter, provided that the ratio of the intake velocity to the velocity at the CSSS is kept the same.

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Minimum pump submergence to prevent surface vortex formation

Cited by 22 publications

References 5 publications

Occurrence Condition of Air Entrainment into a Vertical Wet-Pit Pump

Occurrence Condition of Air Entrainment into a Vertical Wet-Pit Pump

Effects of dimensionless parameters on air-entraining vortices

Effects of Froude, Reynolds, and Weber numbers on an air-entraining vortex

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