Flow Visualization of Submerged Steam Jet in Subcooled Water

2016 ◽  
Vol 138 (2) ◽  
Author(s):  
Fang Yuan ◽  
Quanbin Zhao ◽  
Daotong Chong ◽  
Weixiong Chen
Keyword(s):  
Nuclear Reactor ◽  
Bubble Diameter ◽  
Flow Region ◽  
Pressure Oscillation ◽  
Transfer Characteristic ◽  
Dominant Frequency ◽  
Phase Region ◽  
Two Phase ◽  
Penetration Length ◽  
Subcooled Water

Steam discharged into subcooled water is investigated experimentally to demonstrate the direct contact condensation phenomena in nuclear reactor safety system and underwater propulsion apparatus. The steam jet condenses to various shapes at different thermal hydraulic conditions. A condensation regime diagram is drawn to classify the regime for different flow patterns, among which there are three typical shapes of steam plume characterizing the chugging, condensation oscillation, stable condensation regime (Figure 1). The flow region can be separated into three parts—vapor, water and two-phase regions, and the white patch in the image indicating the two-phase region is a mixture of condensed vapor and subcooled water. Three typical stages of bubble motions—growth (subimage 1 to 6, Figure 2), necking (subimage 7 to 10, Figure 2), and detachment (subimage 11 to 13, Figure 2)—are demonstrated. The bubble diameter reaches the maximum at the necking stage and remains approximately invariant with the connecting neck prolonging for a period. A series of sequent photos exhibits shape transformations at the stable condensation regime, implying that the steam plume grows and shortens periodically due to comprehensive effects of injection, viscosity damping and condensation (Figure 3). The dimensionless penetration length, defined as the ratio of penetration length to nozzle diameter, is in the range of 8.23–11.67 in the Figure 3. The majority of previous literatures present the average dimensionless penetration length which is closely related with time-averaged heat transfer characteristic. However, variations of steam plume are proven to account for pressure oscillation phenomena by the transient visualization investigations, in which the first dominant frequency acquired from the FFT domain graph of pressure signal is consistent with the period of steam plume variations. The second dominant frequency is verified to be caused by oscillations of detached bubbles (subimage 8 and 9, Figure 3) in the research.

scholarly journals Inclined Injection of Supersonic Steam into Subcooled Water: A CFD Analysis

2013 ◽  
Vol 845 ◽  
pp. 101-107 ◽  
Author(s):  
Afrasyab Khan ◽  
Khairuddin Sanaullah ◽  
M. Sobri Takriff ◽  
Hushairi Zen ◽  
Lim Soh Fong
Keyword(s):  
Direct Contact ◽  
Nuclear Reactor ◽  
Bubble Diameter ◽  
Supersonic Nozzle ◽  
Industrial Applications ◽  
Heat Transfer Process ◽  
Multiphase Model ◽  
Contact Heat ◽  
Penetration Length ◽  
Subcooled Water

The phenomenon of direct-contact condensation gains attention because of various industrial applications; nuclear reactor emergency core cooling systems,steam driven jet injectors, direct-contact heat exchangers etc..The phenomenon was investigated computationally by injecting an inclined steam jet using a supersonic nozzle submerged in subcooled water. The condensation mechanism is based on two resistance model, which involves consideration of the heat transfer process on both sides of the interface along with use of a variable steam bubble diameter. For computations, ANSYS Fluent based Euler-Euler multiphase model is used. The angle of inclination varies from 5oto 45oat constant inlet pressure of 7 bars with water temperature of 30°C. The maximum penetration length is achieved using a right angled vertical injection.

Critical Two-Phase Flow in Pipes for Subcooled Stagnation States With a Cavity Flooding Incipient Flashing Model

1990 ◽  
Vol 112 (4) ◽  
pp. 1032-1040 ◽  
Author(s):  
S. Y. Lee ◽  
V. E. Schrock
Keyword(s):  
Nuclear Reactor ◽  
Safety Evaluation ◽  
Phase Region ◽  
Dominant Factor ◽  
Critical Flow ◽  
Primary System ◽  
Transient Heating ◽  
Two Phase ◽  
Flow Process ◽  
Sequence Of Events

Analysis of loss of coolant accident (LOCA) scenarios in nuclear reactor safety evaluation depends on knowledge of many complex phenomena. A primary phenomenon controlling the sequence of events, by determining the residual coolant mass inventory within the primary system, is the critical flow process. Critical flow of a flashing liquid is complicated by marked departure from thermal equilibrium. Several complex models have been proposed to represent the non-equilibrium effects, including six-equation two-fluid models. Amos and Schrock (1983) developed a model based on the premise that the two-phase region is homogeneous and that thermal nonequilibrium is the dominant factor causing the departure from the homogeneous equilibrium idealization. Flashing inception was represented by a modification of the Alamgir-Lienhard (1981) pressure undershoot. Exponential relaxation of the metastable liquid was formulated as suggested by Bauer et al. (1976) and the critical flow criterion used the sound speed formulation of Kroeger (1976). Lee and Schrock (1988) extended the Amos-Schrock work by developing an improved correlation for the pressure undershoot correction factor in terms of Reynolds number and subcooling Jakob number. Improvements were also made in the relaxation constant and in the application of Kroeger’s formulation. In the present paper a new cavity flooding model is used for the evaluation of pressure undershoot at flashing inception. This model is similar to the one developed by Fabic (1964) for the evaluation of liquid superheat required for boiling on a surface subjected to transient heating. The model contains an experimentally deduced factor, which is correlated against stagnation subcooling using the experimental data of Amos and Schrock (1983, 1984), Jeandey et al. (1981), and the Marviken tests (Anon., 1979). The model was then tested against seven additional data sets and shown to be very accurate in predicted mass flux (standard deviation of 10.9 percent for all data). The cavity flooding model is thought to represent the true physics more correctly than does the earlier model, which had its origin in molecular fluctuation theory.

Research Status of Physical Simulation on LF Furnace Refining Ladle

2014 ◽  
Vol 678 ◽  
pp. 616-619
Author(s):  
Xiao Lei Zhou ◽  
Zhe Shi ◽  
Gui Fang Zhang ◽  
Zhong Ning Du
Keyword(s):  
Flow Field ◽  
Recirculation Zone ◽  
Physical Simulation ◽  
Flow Region ◽  
Phase Region ◽  
Flow Zone ◽  
Two Phase ◽  
Research Status ◽  
Similarity Principle ◽  
Flow Field Measurement

The research status of physical simulation on LF furnace refining ladle is introduced in this paper.Since 1970, the research on the gas-liquid two-phase region has begun. The ladle of blowing argon can be roughly divided into three important flow region has been introduced. Two-phase region, the top horizontal flow zone and recirculation zone exists in the ladle.The establishment of physical model should include similarity principle and flow field measurement technique

On the Numerical Study of Bubbly Flow Created by Ventilated Cavity

2010 ◽  
Vol 29-32 ◽  
pp. 143-148
Author(s):  
Min Xiang ◽  
S.C.P. Cheung ◽  
Ji Yuan Tu ◽  
Wei Hua Zhang ◽  
Yang Fei
Keyword(s):  
Flow Field ◽  
Void Fraction ◽  
Numerical Study ◽  
Fluid Model ◽  
Bubbly Flow ◽  
Bubble Diameter ◽  
Flow Region ◽  
Valuable Insight ◽  
Two Phase ◽  
Ventilated Cavity

The aim of the study was to develop a numerical model to reproduce the bubbly flow field created by ventilated cavity which includes three different regions. The model was established based on the Eulerian-Eulerian two-fluid model coupled with a population balance approach which is solved by the Homogeneous Multiple-Size-Group (MUSIG) model to predict bubble size distribution. Base on the model, the simulation was carried out at the experimental condition of Su et al. (1995). Firstly three regions were successfully captured proved by the spatial voidage distribution and streamline shape. Then distributions of void fraction and Sauter mean bubble diameter at various sections below the cavity corresponding to three regions respectively were plotted against experimental data. A close agreement was observed in the void fraction distribution which indicates that qualitative details of the structure of the two-phase flow field below the cavity was successfully produced. The Sauter mean bubble diameter in the pipe flow region was under-predicted for about 10%. In conclusion, the proposed model was validated in predicting the multi-region flow field below the ventilated cavity which will provide a valuable insight in designing and controlling of the two phase systems with the detailed flow field information obtained.

Argon Blowing Technology Using in the LF Refining

2014 ◽  
Vol 696 ◽  
pp. 66-69
Author(s):  
Xiao Lei Zhou ◽  
Zhe Shi ◽  
Gui Fang Zhang
Keyword(s):  
Recirculation Zone ◽  
Flow Region ◽  
Phase Region ◽  
Temperature Uniformity ◽  
Flow Zone ◽  
Material Transfer ◽  
Steel Composition ◽  
Two Phase ◽  
Deoxidation Product ◽  
Lf Refining

The process of LF Refining is introduced in this paper. Because the LF ladle furnace has the advantages are widely used and developed in many companies. The argon is blown into the ladle, so the purpose of refining is achieved. The argon stirring can accelerate the chemical reaction between slag and steel. In the circulation process, large inclusion and deoxidation product in the lower region transfer into the slag. The material transfer between steel and slag can be accelerated. At the same time, argon stirring can make molten steel composition and temperature uniformity. Thus, the ladle of blowing argon can be roughly divided into three important flow region has been introduced. Two-phase region, the top horizontal flow zone and recirculation zone exists in the ladle.

Core Ignition Prediction With Moving Two-Phase Zone Boundaries

2008 ◽  
Author(s):  
Dov Hasan ◽  
Yuri Nekhamkin ◽  
Eitan Wacholder ◽  
Ezra Elias
Keyword(s):  
Nuclear Reactor ◽  
Reactor Core ◽  
Phase Region ◽  
Transient Temperature ◽  
Phase Zone ◽  
Two Phase ◽  
Loss Of Coolant Accident ◽  
Hydraulic Behaviour ◽  
Nuclear Reactor Core ◽  
Accident Conditions

The interaction between a fuel rod metal clad and the surrounding steam in a nuclear reactor core under hypothetical accident conditions is considered using a thermal balance based model. This enables the calculation of the metal transient temperature and its rate of oxidation, which may possibly lead to ignition and rapid burning. The transient fluid thermal-hydraulic behaviour of the two phase region, as well as the propagation in space and time of its boundaries following a step change in the coolant inlet mass flow rate are solved using a one-dimensional, two-phase homogeneous flow model. The solution scheme consists of first solving the velocity field analytically followed by a numerical solution of the remaining balance equations for the density field. The transient location of the dry-zone region, as well as the other flow primary variables; i.e., vapour quality, and enthalpy are then directly obtained. Numerical results are illustrated based on input data of a partially uncovered AP600 type nuclear reactor core during a bottom-reflooding phase of a loss of coolant accident scenario.

scholarly journals Depressurization of Vertical Pipe with Temperature Gradient Modeled with WAHA Code

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Oriol Costa ◽  
Iztok Tiselj ◽  
Leon Cizelj
Keyword(s):  
Temperature Gradient ◽  
Pressure Wave ◽  
Ambient Pressure ◽  
Bubble Diameter ◽  
Phase Region ◽  
Pressure Amplitude ◽  
Two Phase ◽  
Pressurized Water ◽  
Pressure Wave Amplitude

The subcooled decompression under temperature gradient experiment performed by Takeda and Toda in 1979 has been reproduced using the in-house code WAHA version 3. The sudden blowdown of a pressurized water pipe under temperature gradient generates a travelling pressure wave that changes from decompression to compression, and vice versa, every time it reaches the two-phase region near the orifice break. The pressure wave amplitude and frequency are obtained at different locations of the pipe's length. The value of the wave period during the first 20 ms of the experiment seems to be correct but the pressure amplitude is overpredicted. The main three parameters that contribute to the pressure wave behavior are: the break orifice (critical flow model), the ambient pressure at the outlet, and the number of volumes used for the calculation. Recent studies using RELAP5 code have reproduced the early pressure wave (transient) of the same experiment reducing the discharge coefficient and the bubble diameter. In the present paper, the long-term pipe pressure, that is, 2 seconds after rupture, is used to estimate the break orifice that originates the pressure wave. The numerical stability of the WAHA code is clearly proven with the results using different Courant numbers.

Thermal Hydraulic and Two-Phase Phenomena in Reflooding of Nuclear Reactor Cores

1984 ◽  
Vol 106 (4) ◽  
pp. 477-485 ◽  
Author(s):  
S. M. Ghiaasiaan ◽  
I. Catton ◽  
R. B. Duffey
Keyword(s):  
Nuclear Reactor ◽  
Phase Region ◽  
Hydraulic Analysis ◽  
Level Variation ◽  
Slab Geometry ◽  
Two Phase ◽  
The Core ◽  
Power Profile ◽  
Implicit Expressions ◽  
Thermal Hydraulic Analysis

A quasi-steady, two-dimensional thermal hydraulic analysis of the two-phase region formed ahead of a quench front during reflooding of a slab or cylindrical core is carried out, and the results for slab geometry are compared with the experiment. It is shown that the two-phase level variation in the core is due to the transverse heat flux power profile, and is sensitive to the assumed pressure-drop boundary condition for the bundle, while the effects of crossflow and axial friction are small. Implicit expressions are given for predicting the quasi-steady two-phase level variation across slab and cylindrical cores.

Solution Properties and Phase Behavior of Ammonium Hexylene Octyl Succinate in Water and Water-Oil System

1970 ◽  
Vol 3 (1) ◽  
Author(s):  
Md. Hamidul Kabir ◽  
Ravshan Makhkamov ◽  
Shaila Kabir
Keyword(s):  
Critical Micelle Concentration ◽  
Phase Behavior ◽  
Liquid Crystalline ◽  
Carbon Number ◽  
Phase Region ◽  
Solution Properties ◽  
Middle Phase ◽  
Two Phase ◽  
Lamellar Liquid Crystal ◽  
Drug Ingredient

The solution properties and phase behavior of ammonium hexylene octyl succinate (HOS) was investigated in water and water-oil system. The critical micelle concentration (CMC) of HOS is lower than that of anionic surfactants having same carbon number in the lipophilic part. The phase diagrams of a water/ HOS system and water/ HOS/ C10EO8/ dodecane system were also constructed. Above critical micelle concentration, the surfactant forms a normal micellar solution (Wm) at a low surfactant concentration whereas a lamellar liquid crystalline phase (La) dominates over a wide region through the formation of a two-phase region (La+W) in the binary system. The lamellar phase is arranged in the form of a biocompatible vesicle which is very significant for the drug delivery system. The surfactant tends to be hydrophilic when it is mixed with C10EO8 and a middle-phase microemulsion (D) is appeared in the water-surfactant-dodecane system where both the water and oil soluble drug ingredient can be incorporated in the form of a dispersion. Hence, mixing can tune the hydrophile-lipophile properties of the surfactant. Key words: Ammonium hexylene octyl succinate, mixed surfactant, lamellar liquid crystal, middle-phase microemulsion. Dhaka Univ. J. Pharm. Sci. Vol.3(1-2) 2004 The full text is of this article is available at the Dhaka Univ. J. Pharm. Sci. website

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