Pressure losses caused by area changes in a single-channel flow under two-phase flow conditions

Tapucu, A.; Teyssedou, A.; Troche, N.; Merilo, M.

doi:10.1016/0301-9322(89)90085-2

“…Particular attention has to be devoted for the modelling of the wall friction force as well as the gravity force required in the momentum balance of the mixture (10). The non negligible contribution of these forces has not been considered in the existing approaches.…”

Section: Expansion Zone Modelmentioning

confidence: 99%

“…(3) By developing the linear momentum balance equation of the mixture (9) which is derived from the basis theorem, claiming that the flux of momentum across the boundaries of the control volume is equal to the resultant of the forces exerted on this control volume, one gets: (10) where t TP is the shear stress exerted on the pipe wall (A pe ) and p c is the mean pressure exerted in the recirculation zone surrounding the vena contracta.…”

Section: Expansion Zone Modelmentioning

confidence: 99%

“…This effective density is a function of the void fraction or the slip ratio at the orifice. On the basis of the momentum and mechanical energy balance laws applied to the gas-liquid flow through an abrupt contraction, Weisman et al [7], AlFerov and Shul'Zhenko [8], Chen et al [9] and Tapucu et al [10] have obtained formulations taking into account the slip motion between the two fluids. These separated-phase models need the knowledge of the void fraction or the slip ratio at the vicinity of the abrupt area change.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A Model for Pressure Drop of Gas-Liquid Bubbly Flow through an Orifice or an Abrupt Pipe Contraction

Attou¹,

Bolle²

1999

Chem. Eng. Technol.

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A new physical model is developed to predict the pressure drop of a steady-state gas-liquid bubbly flow through an orifice or an abrupt pipe contraction. The formulation of the model involves balance equations deduced from the macroscopic mass, momentum, entropy and energy conservation laws as well as a balance of forces exerted on the dispersed bubbles phase. The thermal equilibrium between phases is assumed but the gas-liquid slip motion is taken into account. The gas-liquid interaction and the wall shear stress are evaluated from theoretical considerations. The predictions of pressure drop from the model are found to be in good agreement with several experimental data of the literature obtained for bubbly air-water flows through orifices. In agreement with the experimental observations, the theoretical predictions show that the two-phase pressure drop multiplier is not strongly influenced by the pipe diameter and increases slightly with the cross-sectional area ratio of the orifice. An essential feature of the present model is the absence of adjustable constants.

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“…The structure of the inlet box of the air cooling condenser is showed in Fig.1. Pressure drops associated with single-phase flow through abrupt flow area changes in commonly-applied large systems have been extensively studied in the past [3,4] .…”

Section: Introduction and The Aim Of The Papermentioning

confidence: 99%

Optimization of air-cooling condenser in close-loop self-circulating evaporative cooling system of large electrical equipments

Li¹,

Song²,

Gu³

2009

2009 International Conference on Electrical Machines and Systems

1

0

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Close-loop self-circulating(CLSC) evaporative cooling technology is a newly developed cooling technique in the evolution of large electrical machines and other large electrical equipments. As the driving power of the coolant in the circulating loop of the self-circulating evaporative cooling system is very small, each part of the resistance must be studied thoroughly to minimize them. This paper is devoted to the optimization of the air cooling condenser used in the CLSC evaporative cooling system of the large electrical equipment. Different types of the inlet box of the air cooling condenser are studied by both numerical simulations and experiments. By doing these, an optimal structure of the inlet box of the air cooling condenser is obtained, and it can do certain helps in the development of the evaporative cooling technology.

show abstract

“…This effective density is a function of the void fraction or the slip ratio at the orifice. On the basis of the momentum and mechanical energy balance laws applied to the gas-liquid flow through an abrupt contraction, Weisman et al [7], AlFerov and Shul'Zhenko [8], Chen et al [9] and Tapucu et al [10] have obtained formulations taking into account the slip motion between the two fluids. These separated-phase models need the knowledge of the void fraction or the slip ratio at the vicinity of the abrupt area change.…”

Section: Introductionmentioning

confidence: 99%

A Model for Pressure Drop of Gas-Liquid Bubbly Flow through an Orifice or an Abrupt Pipe Contraction

Attou¹,

Bolle²

1999

Chem. Eng. Technol.

0

View full text Add to dashboard Cite

A new physical model is developed to predict the pressure drop of a steady-state gas-liquid bubbly flow through an orifice or an abrupt pipe contraction. The formulation of the model involves balance equations deduced from the macroscopic mass, momentum, entropy and energy conservation laws as well as a balance of forces exerted on the dispersed bubbles phase. The thermal equilibrium between phases is assumed but the gas-liquid slip motion is taken into account. The gas-liquid interaction and the wall shear stress are evaluated from theoretical considerations. The predictions of pressure drop from the model are found to be in good agreement with several experimental data of the literature obtained for bubbly air-water flows through orifices. In agreement with the experimental observations, the theoretical predictions show that the two-phase pressure drop multiplier is not strongly influenced by the pipe diameter and increases slightly with the cross-sectional area ratio of the orifice. An essential feature of the present model is the absence of adjustable constants.

show abstract

Pressure losses caused by area changes in a single-channel flow under two-phase flow conditions

Cited by 17 publications

References 10 publications

A Model for Pressure Drop of Gas-Liquid Bubbly Flow through an Orifice or an Abrupt Pipe Contraction

A Model for Pressure Drop of Gas-Liquid Bubbly Flow through an Orifice or an Abrupt Pipe Contraction

Optimization of air-cooling condenser in close-loop self-circulating evaporative cooling system of large electrical equipments

A Model for Pressure Drop of Gas-Liquid Bubbly Flow through an Orifice or an Abrupt Pipe Contraction

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