Numerical Simulations of Two-Phase Flow in a Fuel Assembly of Blockage due to LOCA

2017 ◽  
Author(s):  
Jingwen Ren ◽  
Fenglei Niu ◽  
Weiqian Zhuo ◽  
Da Wang
Keyword(s):  
Pressure Drop ◽  
Numerical Simulations ◽  
Fuel Assembly ◽  
Water Flow ◽  
Two Phase Flow ◽  
Volume Fraction ◽  
Particle Diameter ◽  
High Energy ◽  
Phase Flow ◽  
Two Phase

During a LOCA accident, the debris caused by the action of high energy fluid discharged from the break may transport to the containment sump, then may be entrained into the core by the ECCS water. The debris may cause the blockage of fuel assembly. The air may also enter the reactor with water. Numerical simulations are performed to analyze the air-water flow and particle-water flow through the blocked fuel assembly. The pressure drop in fuel assembly will impact the long-term core cooling capability. The effects of different parameters on the pressure drop over the fuel assembly are analyzed. Pressure drop increases as blockage percentage, mass flow rate or inlet velocity increases for both two-phase flow. The decrease of air volume fraction and the increase of particle volume fraction all cause the increase of pressure drop. Pressure drop increases slightly as bubble diameter increases, and the tiny effect of particle diameter on pressure drop was found as particle diameter varying at an increment of 10um.

Numerical Investigation of Two-Phase Flow Over Unglazed Plate Collector Covered With Porous Material of Wire Screen for Solar Water Heater Application

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
T. Salameh ◽  
Y. Zurigat ◽  
A. Badran ◽  
C. Ghenai ◽  
M. El Haj Assad ◽  
...  
Keyword(s):  
Surface Tension ◽  
Porous Material ◽  
Water Flow ◽  
Two Phase Flow ◽  
Volume Fraction ◽  
Phase Flow ◽  
Two Phase ◽  
Solar Water ◽  
Wire Screen ◽  
Effect Of Surface

This paper presents three-dimensional numerical simulation results of the effect of surface tension on two-phase flow over unglazed collector covered with a wire screen. The homogenous model is used to simulate the flow with and without the effect of porous material of wire screen and surface tension. The Eulerian-Eulerian multiphase flow approach was used in this study. The phases are completely stratified, the interphase is well defined (free surface flow), and interphase transfer rate is very large. The liquid–solid interface, gas–liquid interface, and the volume fraction for both phases were considered as boundaries for this model. The results show that the use of porous material of wire screen will reduce the velocity of water flow and help the water flow to distribute evenly over unglazed plate collector. The possibility of forming any hot spot region on the surface was reduced. The water velocity with the effect of surface tension was found higher than the one without this effect, due to the extra momentum source added by surface tension in longitudinal direction. The use of porous material of wires assures an evenly distribution flow velocity over the inclined plate, therefore helps a net enhancement of heat transfer mechanism for unglazed solar water collector application.

scholarly journals Numerical and experimental studies of gas–liquid flow and pressure drop in multiphase pump valves

2020 ◽  
Vol 103 (3) ◽  
pp. 003685042094088
Author(s):  
Yi Ma ◽  
Minjia Zhang ◽  
Huashuai Luo
Keyword(s):  
Pressure Drop ◽  
Two Phase Flow ◽  
Volume Fraction ◽  
Test System ◽  
Ball Valve ◽  
Phase Flow ◽  
Two Phase ◽  
Pressure Drops ◽  
Disk Valve ◽  
Predicted Values

A numerical and experimental study was carried out to investigate the two-phase flow fields of the typical three valves used in the multiphase pumps. Under the gas volume fraction conditions in the range of 0%–100%, the three-dimensional steady and dynamic two-phase flow characteristics, pressure drops, and their multipliers of the ball valve, cone valve, and disk valve were studied, respectively, using Eulerian–Eulerian approach and dynamic grid technique in ANSYS FLUENT. In addition, a valve test system was built to verify the simulated results by the particle image velocimetry and pressure test. The flow coefficient CQ (about 0.989) of the disk valve is greater than those of the other valves (about 0.864) under the steady flow with a high Reynolds number. The two-phase pressure drops of the three valves fluctuate in different forms with the vibration of the cores during the dynamic opening. The two-phase multipliers of the fully opened ball valve are consistent with the predicted values of the Morris model, while those of the cone valve and disk valve had the smallest differences with the predicted values of the Chisholm model. Through the comprehensive analysis of the flow performance, pressure drop, and dynamic stability of the three pump valves, the disk valve is found to be more suitable for the multiphase pumps due to its smaller axial space, resistance loss, and better flow capacity.

Experimental and numerical study of air-water flow characteristics in a horizontal duct

2020 ◽  
pp. 095440622093631
Author(s):  
Mohamed H Mansour ◽  
Ali A Zahran ◽  
Lotfy H Rabie ◽  
Ibrahim M Shabaka
Keyword(s):  
Water Flow ◽  
Two Phase Flow ◽  
Volume Fraction ◽  
Phase Distribution ◽  
Electronic Device ◽  
Pipe Wall ◽  
Numerical Study ◽  
Bubble Velocity ◽  
Phase Flow ◽  
Two Phase

The horizontal bubbly two-phase flow is preferably used in various industrial applications because it provides high interfacial areas which enhance the heat and mass transfer. In the present research, the phase distribution of controlled air-water flow in a horizontal acrylic round pipe with 60 mm inside diameter (D) has been investigated experimentally and modeled numerically. The modeled differential pressure and the mixture velocity profile at a distance of 33D from the mixing section (fully developed region) are computed numerically and compared with those obtained experimentally from the two-phase flow system established and maintained at the National Institute of Standards (NIS-Egypt). Furthermore, the numerical and the experimental data have been compared with previous correlations and models. Reasonable quantitative agreement between all data is found. An electronic device based on Arduino Uno board was designed and used with careful data manipulation for measuring the slug bubble velocity. The results point out that the air volume fraction has a maximum value at the upper pipe wall as the gas bubbles tend to migrate to the upper wall. A new correlation was obtained for bubble migration length to the upper pipe wall which is very important in chemical industrial processes and other engineering application.

Evaluation of Liquid-Gas Two-Phase Flow Pressure Drop Signatures in Proton Exchange Membrane (PEM) Fuel Cell Flow Channels

2018 ◽  
Author(s):  
Mehdi Mortazavi ◽  
Jingru Benner ◽  
Anthony Santamaria
Keyword(s):  
Fuel Cell ◽  
Pressure Drop ◽  
Water Flow ◽  
Flow Rate ◽  
Two Phase Flow ◽  
Pem Fuel Cell ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Rates ◽  
Flow Pressure

In this study, liquid-gas two-phase flow pressure drops were measured in an ex-situ PEM fuel cell test section. Pressure drop signatures were studied for three nominal air flow rates and different water flow rates within a flow channel. The pressure drop signatures showed an increasing trend at the beginning of the experiments which were followed by a drop to lower values before reaching uniform patterns. It was observed that as the water flow rate increased, the time interval at which pressure signatures reached uniform patterns decreased. In addition, a qualitative comparison with Mishima-Hibiki model [13] revealed that this two-phase flow pressure drop model showed the best prediction capability for the medium air flow rate used in this study, ∼300mℓ/min inflow channel, corresponding to ∼220 Reynolds number.

Developing Lengths in Horizontal Two-Phase Bubbly Flow

1995 ◽  
Vol 117 (3) ◽  
pp. 512-518 ◽  
Author(s):  
B. A. Warren ◽  
J. F. Klausner
Keyword(s):  
Pressure Drop ◽  
Two Phase Flow ◽  
Volume Fraction ◽  
Bubbly Flow ◽  
Phase Flow ◽  
Flow Conditions ◽  
Relative Deviation ◽  
Two Phase ◽  
Fully Developed Flow ◽  
Local Measurements

An air-water two-phase flow facility with a 19.1 mm i.d. test section has been fabricated. Local measurements of pressure drop for two-phase horizontal bubbly flow and single-phase flow downstream of various orifices have been obtained over a range of flow conditions. The wall shear stress developing length is obtained from the pressure drop profile. A developing length correlation is presented in which the relative deviation is 6 percent. The fully developed vapor volume fraction has also been measured up- and downstream of the orifice. A simple correlation for vapor volume fraction is presented in which the relative deviation is 7 percent. Photographs of the two-phase flow pattern in the developing region reveal that the flow structure is extremely complex and continuously evolves until approximately fully developed flow conditions are achieved.

Single Phase and Two-Phase Flow Pressure Drop in Pebble Beds

2010 ◽  
Author(s):  
Bofeng Bai ◽  
Maolong Liu ◽  
Xiaofei Lv ◽  
Wang Su ◽  
Xiao Yan ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Gas Phase ◽  
Single Phase ◽  
Two Phase Flow ◽  
Particle Diameter ◽  
Spherical Particles ◽  
Phase Flow ◽  
Two Phase ◽  
Pressure Drops ◽  
Flow Pressure

An experimental study was conducted on the pressure drop of single phase and air-water two-phase flow in the bed of rectangular cross sections filled with uniform spheres densely. In the present flow-regime model, the bed was subdivided into a near-wall region and a central region. And a new empirical correlation for the prediction of single-phase flow pressure drops was proposed based on the model. The correlation can be used to predict the single phase pressure drop for both great tube-to-particle diameter ratio packed beds and small tube-to-particle diameter ratio packed beds and for the pebble beds packing with spherical particles and non spherical particles. A new empirical correlation for the prediction of two-phase flow pressure drops was proposed based on the gas phase relative permeability as a function of the gas phase saturation and the void fraction. The correlation fit well also for both experimental data points of spherical particles and non spherical particles.

Pressure Drop for Oil-Gas Two-Phase Flow Through Straight Horizontal Pipe

2007 ◽  
Author(s):  
Wenhong Liu ◽  
Liejin Guo ◽  
Ximin Zhang ◽  
Kai Lin ◽  
Long Yang ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Flow Through ◽  
Oil Gas
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