A HOMOGENEOUS NON-EQUILIBRIUM TWO-PHASE CRITICAL FLOW MODEL FOR THE ANALYSIS OF SUPERSONIC JET FLOW

Mechanical non-homogeneous and thermal non-equilibrium phenomenon exists in two-phase critical flow compared with single phase flow. A one-dimensional two-fluid critical flow model is developed for initially subcooled water flowing in pipe or orifices. The model accounts for thermal nonequilibrium between the liquid and vapor bubbles and for interphase relative motion. In this model, an improved correlation to calculate flashing inception location and surperheat is proposed. The model consists of six conservation equations as well as a seventh equation representing bubble growth in bubbly flow. Closure of the set of governing equations is performed with constitutive relationships which determine the interfacial momentum terms due to mass exchange, wall to liquid and wall to vapour frictional forces, liquid to gas interfacial force and interfacial heat transfer rate. The model considers the development of three flow regimes, namely, bubbly, churn and annular flow regimes. Model predictions compare favorably with experimental data over a wide range of pressures and pipe diameters and lengths.

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Development of a new full-range critical flow model based on non-homogeneous non-equilibrium model

Annals of Nuclear Energy ◽

10.1016/j.anucene.2021.108286 ◽

2021 ◽

Vol 158 ◽

pp. 108286

Author(s):

Hong Xu ◽

Aurelian Florin Badea ◽

Xu Cheng

Keyword(s):

Equilibrium Model ◽

Flow Model ◽

Full Range ◽

Critical Flow ◽

Model Based ◽

Non Equilibrium

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Evaluation of Two-Phase Critical Flow Model Based on the RETRAN-3D and RELAP5/MOD4.0

Nuclear Science and Technology ◽

10.12677/nst.2015.33013 ◽

2015 ◽

Vol 03 (03) ◽

pp. 88-96

Author(s):

诚赖

Keyword(s):

Flow Model ◽

Critical Flow ◽

Two Phase ◽

Model Based

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Two-Phase Critical Flow under Diabatic Conditions

Proceedings of the Institution of Mechanical Engineers Conference Proceedings ◽

10.1243/pime_conf_1969_184_088_02 ◽

1969 ◽

Vol 184 (3) ◽

pp. 127-133

Author(s):

A. E. Bergles ◽

J. T. Kelly

Keyword(s):

Experimental Investigation ◽

Equilibrium Model ◽

Small Diameter ◽

Critical Flow ◽

Subcooled Boiling ◽

Flow Conditions ◽

Two Phase ◽

Wide Range ◽

Good Agreement ◽

Non Equilibrium

This paper summarizes an experimental investigation of steam-water critical flow in heated tubes. A wide range of data was taken for water at pressures below 100 lbf/in2 (abs.) in tubes of small diameter. It is demonstrated that critical flow conditions can occur in subcooled boiling at low exit subcoolings. At equilibrium qualities below about 0·04, the data differ significantly from adiabatic data for a similar exit geometry. The deviations can be explained in terms of the additional non-equilibrium effects present in heated flows. For higher qualities, the diabatic data are in good agreement with adiabatic data, and can be approximately predicted by a slip equilibrium model.

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Mechanical Non-Equilibrium Effect on Choking Flow at Low Pressure in Air-Water Experiment

10th International Conference on Nuclear Engineering, Volume 3 ◽

10.1115/icone10-22526 ◽

2002 ◽

Cited By ~ 1

Author(s):

H. J. Yoon ◽

M. Ishii ◽

S. T. Revankar ◽

W. Wang

Keyword(s):

Mass Flux ◽

Critical Mass ◽

Low Pressure ◽

Low Flow ◽

Critical Flow ◽

Two Phase ◽

Slip Ratio ◽

Flow Quality ◽

Equilibrium Effect ◽

Non Equilibrium

At low pressure and low flow conditions, the prediction of two-phase flow transients is much more difficult than at relatively higher pressure or at high flow due to the large density ratio and thermal and mechanical non-equilibrium between the phases. A mechanical non-equilibrium effect was studied with air-water two-phase critical flow in pipes at low pressure (< 1 MPa). Critical flow test were conducted in a well-scaled test facility with several on-line instruments. The slip ratio, which is the key factor in the mechanical non-equilibrium, is directly measured at the upstream of the critical section. The break geometry effect was investigated using the nozzle and orifice as critical flow sections. The experimental results showed that the slip ratio increased as the quality increased. The slip ratio value at low pressure was relatively higher than the slip ratio at the high pressure for the same flow quality. The measured critical mass flux for the nozzle was higher than the orifice at the low flow quality. Thus there is a geometry effect on critical mass flux at the low quality region, even though there is no difference in the slip ratio at the upstream of choking plane. Thus, it is concluded that there is a strong mechanical non-equilibrium at the choking plane.

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