Hydrodynamic Forces, Pressure and Mass Flux in Two-Phase Air-Water Flow Through Transparent Safety Valve Model

2010 ◽  
Author(s):  
Vasilios Kourakos ◽  
Sai¨d Chabane ◽  
Patrick Rambaud ◽  
Jean-Marie Buchlin
Keyword(s):  
Single Phase ◽  
Safety Valve ◽  
Flow Behavior ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Two Phase ◽  
Flow Through ◽  
Static Flow ◽  
Valve Model ◽  
Made In

Safety devices are of major importance in the nuclear and chemical industry. Examples of such systems are safety valves and rupture disks. The behavior of this type of valve in single-phase flow (gas or liquid) has been described in detail in the literature, while for two-phase flow there is a lack of relative models since the phenomena are much more complex. The design and sizing of this apparatus is an important issue which would prevent its wrong functionality that could cause a hazardous situation. In this paper, a transparent (made in Polymethyl methacrylate) model of a safety valve is studied (1 1/2 in G 3 in); this has allowed full optical access and therefore the identification of the structure of the flow and the observation of the different phenomena occurring. Instead of a spring, used in an actual safety valve, the disk is fixed and its position can vary from completely closed to fully opened position. Thus, the static flow behavior of the valve is examined.

Acoustical Characteristics of Single and Two-Phase Horizontal Pipe Flow Through an Orifice

2017 ◽  
Author(s):  
S. P. C. Belfroid
Keyword(s):  
Multiphase Flow ◽  
Single Phase ◽  
Two Phase Flow ◽  
Jet Noise ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Choked Flow ◽  
Flow Through

In this work, the acoustic effects of horizontal air-water flow through an orifice are investigated experimentally. Single phase flow (air) and two-phase flow (air and water) tests are performed for two sets of orifices. One set of straight edged and one set of upstream rounded orifices. For each set, the diameters of the orifices were 2, 5, and 10mm, with a thickness of 5 mm. The two-phase flow is generated by injecting water at a rate of 0 to 40 g/s to air in a pipe with diameter of 25 mm. The air rate is fixed in the range from 5.8 to 14 g/s, where the upstream pressure varies from 1.5 to 4 bar at ambient temperature. Unsteady pressure fluctuations are recorded at two upstream and two downstream position. The valve noise standard NEN-EN-IEC (60534-8-3, 2011) for dry gas is assessed by means of experimental data in dry conditions at fixed air mass flow rate. Predictions of sound power spectra by means of the standard are found to be more accurate compared to those obtained following Reethof & Ward (1986), also in conditions of a choked orifice. In case of multiphase flow already at very low liquid fractions of much less than 1%, the standard is no longer valid. The frequency spectrum is no longer determined by the jet noise but starts to be dominated by low frequency general multiphase flow. The Strouhal number based on the jet conditions is an order lower than Sr = 0.2 indicating process variations rather than jet noise. Furthermore, at choking conditions the further expansion which occurs in single phase flow is likely different at multiphase flow. For non-choked flow, the standard can be adapted using multiphase mixture properties. This does lead to a good prediction. However at choked conditions, this method fails.

Predicting Single-Phase and Two-Phase Non-Newtonian Flow Behavior in Pipes

1998 ◽  
Vol 120 (1) ◽  
pp. 2-7 ◽  
Author(s):  
R. D. Kaminsky
Keyword(s):  
Single Phase ◽  
Two Phase Flow ◽  
Flow Behavior ◽  
Small Diameter ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Two Phase ◽  
Shear Thinning Fluids ◽  
Diameter Pipe ◽  
Effect Of Surface

Improved and novel prediction methods are described for single-phase and two-phase flow of non-Newtonian fluids in pipes. Good predictions are achieved for pressure drop, liquid holdup fraction, and two-phase flow regime. The methods are applicable to any visco-inelastic non-Newtonian fluid and include the effect of surface roughness. The methods utilize a reference fluid for which validated models exist. For single-phase flow, the use of Newtonian and power-law reference fluids are illustrated. For two-phase flow, a Newtonian reference fluid is used. Focus is given to shear-thinning fluids. The approach is theoretically based and is expected to be more accurate for large, high-pressure pipelines than present correlation methods, which are all primarily based on low-pressure, small-diameter pipe experimental data.

Upward Vertical Two-Phase Flow Through an Annulus—Part II: Modeling Bubble, Slug, and Annular Flow

1992 ◽  
Vol 114 (1) ◽  
pp. 14-30 ◽  
Author(s):  
E. F. Caetano ◽  
O. Shoham ◽  
J. P. Brill
Keyword(s):  
Flow Pattern ◽  
Annular Flow ◽  
Two Phase Flow ◽  
Flow Behavior ◽  
Bubble Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Through ◽  
Physical Phenomena ◽  
Good Agreement

Mechanistic models have been developed for each of the existing two-phase flow patterns in an annulus, namely bubble flow, dispersed bubble flow, slug flow, and annular flow. These models are based on two-phase flow physical phenomena and incorporate annulus characteristics such as casing and tubing diameters and degree of eccentricity. The models also apply the new predictive means for friction factor and Taylor bubble rise velocity presented in Part I. Given a set of flow conditions, the existing flow pattern in the system can be predicted. The developed models are applied next for predicting the flow behavior, including the average volumetric liquid holdup and the average total pressure gradient for the existing flow pattern. In general, good agreement was observed between the experimental data and model predictions.

Experimental Study on Heat Transfer of Single-Phase Flow and Boiling Two-Phase Flow in Vertical Narrow Annuli

2002 ◽  
Author(s):  
Suizheng Qiu ◽  
Minoru Takahashi ◽  
Guanghui Su ◽  
Dounan Jia
Keyword(s):  
Heat Transfer ◽  
Single Phase ◽  
Two Phase Flow ◽  
Annular Channel ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Transfer Coefficients ◽  
Two Phase ◽  
Narrow Annuli ◽  
Narrow Gaps

Water single-phase and nucleate boiling heat transfer were experimentally investigated in vertical annuli with narrow gaps. The experimental data about water single-phase flow and boiling two-phase flow heat transfer in narrow annular channel were accumulated by two test sections with the narrow gaps of 1.0mm and 1.5mm. Empirical correlations to predict the heat transfer of the single-phase flow and boiling two-phase flow in the narrow annular channel were obtained, which were arranged in the forms of the Dittus-Boelter for heat transfer coefficients in a single-phase flow and the Jens-Lottes formula for a boiling two-phase flow in normal tubes, respectively. The mechanism of the difference between the normal channel and narrow annular channel were also explored. From experimental results, it was found that the turbulent heat transfer coefficients in narrow gaps are nearly the same to the normal channel in the experimental range, and the transition Reynolds number from a laminar flow to a turbulent flow in narrow annuli was much lower than that in normal channel, whereas the boiling heat transfer in narrow annular gap was greatly enhanced compared with the normal channel.

Two-Phase Flow Behavior in Channels With Sudden Area Change Using Experimental and Computational Approach

2017 ◽  
Author(s):  
Ashish Kotwal ◽  
Che-Hao Yang ◽  
Clement Tang
Keyword(s):  
Experimental Data ◽  
Pressure Drop ◽  
Experimental Analysis ◽  
Single Phase ◽  
Computational Analysis ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Two Phase ◽  
Flow Rates ◽  
Area Change

The current study shows computational and experimental analysis of multiphase flows (gas-liquid two-phase flow) in channels with sudden area change. Four test sections used for sudden contraction and expansion of area in experiments and computational analysis. These are 0.5–0.375, 0.5–0.315, 0.5–0.19, 0.5–0.14, inversely true for expansion channels. Liquid Flow rates ranging from 0.005 kg/s to 0.03 kg/s employed, while gas flow rates ranging from 0.00049 kg/s to 0.029 kg/s implemented. First, single-phase flow consists of only water, and second two-phase Nitrogen-Water mixture flow analyzed experimentally and computationally. For Single-phase flow, two mathematical models used for comparison: the two transport equations k-epsilon turbulence model (K-Epsilon), and the five transport equations Reynolds stress turbulence interaction model (RSM). A Eulerian-Eulerian multiphase approach and the RSM mathematical model developed for two-phase gas-liquid flows based on current experimental data. As area changes, the pressure drop observed, which is directly proportional to the Reynolds number. The computational analysis can show precise prediction and a good agreement with experimental data when area ratio and pressure differences are smaller for laminar and turbulent flows in circular geometries. During two-phase flows, the pressure drop generated shows reasonable dependence on void fraction parameter, regardless of numerical analysis and experimental analysis.

Incorporation of Interfacial Areas in Models of Two-Phase Flow

1999 ◽  
Author(s):  
William G. Gray ◽  
Michael A. Celia
Keyword(s):  
Porous Media ◽  
Hydraulic Conductivity ◽  
Single Phase ◽  
Darcy’S Law ◽  
Darcy's Law ◽  
Hydraulic Gradient ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Α Phase ◽  
Flow Through

The mathematical study of flow in porous media is typically based on the 1856 empirical result of Henri Darcy. This result, known as Darcy’s law, states that the velocity of a single-phase flow through a porous medium is proportional to the hydraulic gradient. The publication of Darcy’s work has been referred to as “the birth of groundwater hydrology as a quantitative science” (Freeze and Cherry, 1979). Although Darcy’s original equation was found to be valid for slow, steady, one-dimensional, single-phase flow through a homogeneous and isotropic sand, it has been applied in the succeeding 140 years to complex transient flows that involve multiple phases in heterogeneous media. To attain this generality, a modification has been made to the original formula, such that the constant of proportionality between flow and hydraulic gradient is allowed to be a spatially varying function of the system properties. The extended version of Darcy’s law is expressed in the following form: qα=-Kα . Jα (2.1) where qα is the volumetric flow rate per unit area vector of the α-phase fluid, Kα is the hydraulic conductivity tensor of the α-phase and is a function of the viscosity and saturation of the α-phase and of the solid matrix, and Jα is the vector hydraulic gradient that drives the flow. The quantities Jα and Kα account for pressure and gravitational effects as well as the interactions that occur between adjacent phases. Although this generalization is occasionally criticized for its shortcomings, equation (2.1) is considered today to be a fundamental principle in analysis of porous media flows (e.g., McWhorter and Sunada, 1977). If, indeed, Darcy’s experimental result is the birth of quantitative hydrology, a need still remains to build quantitative analysis of porous media flow on a strong theoretical foundation. The problem of unsaturated flow of water has been attacked using experimental and theoretical tools since the early part of this century. Sposito (1986) attributes the beginnings of the study of soil water flow as a subdiscipline of physics to the fundamental work of Buckingham (1907), which uses a saturation-dependent hydraulic conductivity and a capillary potential for the hydraulic gradient.

Turbulence Structure of a Liquid-Solid Two-Phase Jet by Means of Laser Techniques

2003 ◽  
Author(s):  
Toshimichi Arai ◽  
Naoki Kudo ◽  
Tsuneaki Ishima ◽  
Ismail M. Youssef ◽  
Tomio Obokata ◽  
...  
Keyword(s):  
Particle Size ◽  
Single Phase ◽  
Two Phase Flow ◽  
Volume Ratio ◽  
Water Phase ◽  
Phase Flow ◽  
Size Discrimination ◽  
Single Phase Flow ◽  
Particle Volume ◽  
Two Phase

Characteristics on particle motion in a liquid-solid two-phase jet flow were studied in the paper. The water jet including glass particle of 389 μm in mean diameter was injected into water bath. The experimental conditions were 0.21% of initial particle volume ratio, 5mm in pipe diameter and 1.84 m/s of mean velocity on outlet of the jet. A laser Doppler anemometer (LDA) with size discrimination was applied for measuring the time serious velocities of the single-phase flow, particle and water phase flow. A particle image velocimetry (PIV) was also applied in the two-phase flow. The normal PIV method can hardly measure the particle size and perform the particle size discrimination. In the experiment, using the gray scales related with the scattering light intensity, measuring method with size discrimination in two-phase flow was carried out. The experimental results show less difference between velocities of single-phase flow and water-phase flow under this low particle volume ratio condition. Particles have the relative motion with the water-phase and large rms velocity. The PIV used in this experiment, which is called multi-intensity-layer-PIV: MILP, can measure water-phase velocity with good accuracy.

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