Operator Action–Induced Two-Phase Flow Condition Resulting in Performance Degradation of Interfacing Passive System

2020 ◽  
pp. 1-17
Author(s):  
Douglas A. Fynan ◽  
Jinhee Park
Keyword(s):  
Flow Condition ◽  
Two Phase Flow ◽  
Performance Degradation ◽  
Phase Flow ◽  
Passive System ◽  
Two Phase ◽  
Operator Action

Axial Mixing in a Novel Perforated Plate Bubble Column

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
S. Dhanasekaran ◽  
T. Karunanithi
Keyword(s):  
Flow Condition ◽  
Single Phase ◽  
Two Phase Flow ◽  
Liquid Velocity ◽  
Bubble Column ◽  
Axial Dispersion ◽  
Phase Flow ◽  
Two Phase ◽  
Dispersion Number ◽  
Superficial Liquid Velocity

This investigation reports the experimental and theoretical results carried out to evaluate the axial dispersion number for an air-water system in a novel hybrid rotating and reciprocating perforated plate bubble column for single phase and two phase flow conditions. Axial dispersion studies are carried out using stimulus response technique. Sodium hydroxide solution is used as the tracer. Effects of superficial liquid velocity, agitation level and superficial gas velocity on axial dispersion number were analyzed and found to be significant. For the single phase (water) flow condition, it is found that the main variables affecting the axial dispersion number are the agitation level and superficial liquid velocity. When compared to the agitation level, the effect of superficial liquid velocity on axial dispersion number is more predominant. The increase in superficial liquid velocity decreases the axial dispersion number. The same trend is shown by agitation level but the effect is less. The rotational movement of the perforated plates enhances the radial mixing in the section; hence, axial dispersion number is reduced. For the two phase flow condition, the increase in superficial liquid velocity decreases the axial dispersion number, as reported in the single phase flow condition. The increase in agitation level decreases the axial dispersion number, but this decreasing trend is non-linear. An increase in superficial gas velocity increases the axial dispersion number. Correlations have been developed for axial dispersion number for single phase and two phase flow conditions. The correlation values are found to concur with the experimental values.

Influences of Impeller Diameter and Diffuser Blades on Air-Water Two-Phase Flow Performance of Centrifugal Pump

2005 ◽  
Author(s):  
Naoki Matsushita ◽  
Akinori Furukawa ◽  
Kusuo Okuma ◽  
Satoshi Watanabe
Keyword(s):  
Centrifugal Pump ◽  
Water Flow ◽  
Flow Rate ◽  
Rotational Speed ◽  
Flow Condition ◽  
High Performance ◽  
Two Phase Flow ◽  
Water Flow Rate ◽  
Phase Flow ◽  
Two Phase

A tandem arrangement of double rotating cascades and single diffuser cascade, proposed as a centrifugal pump with high performance in air-water two-phase flow condition, yields lower head due to the smallness of the impeller outlet in comparison with a impeller with large outlet diameter and no diffuser. Influences of impeller diameter change and installation of diffuser blades on two-phase flow performance were experimentally investigated under the case of the same volute casing. As the result, the similarity law of the diameter of impeller having the similar blade geometry and the rotational speed is satisfied even in two-phase flow condition. Comparing pump performances between a large impeller without diffuser blades and a small one with diffuser blades, higher two-phase flow performance is obtained by controlling the rotational speed of a small impeller with diffuser blades in the range of small water flow rates, while a large impeller with no diffuser gives high performance in the range of high water flow rate and small air flow rate.

Measurement of Two-Dimensional Void Fraction Distributions of Rising Bubbles in a Simulated Sub-Channel by Wire-Mesh Sensors at Conditions of Forced Convective and Stagnant Flows

2017 ◽  
Author(s):  
Yota Suzuki ◽  
Yusei Tanaka ◽  
Taku Sakka ◽  
Akinori Sato ◽  
Kazuyuki Takase ◽  
...  
Keyword(s):  
Flow Condition ◽  
Two Phase Flow ◽  
Flow Behavior ◽  
Wire Mesh ◽  
Phase Flow ◽  
Two Dimensional ◽  
Two Phase ◽  
Fuel Rods ◽  
Fuel Rod ◽  
Stagnant Flow

Clarifying thermal-hydraulic characteristics in a nuclear reactor core is important in particular to enhance the thermo-fluid safety of nuclear reactors. Spacers installed in subchannels of fuel assemblies have the role of keeping the interval between adjacent fuel rods constantly. Similarly, in case of PWR the spacer has also the role as the turbulence promoter. When the transient event occurs, two-phase flow is generated by boiling of water due to heating of fuel rods. Therefore, it is important to confirm the two-phase flow behavior around the spacer. So, the effect of the spacer affecting the two-phase flow was investigated experimentally at forced convective flow condition. Furthermore, in order to improve the thermal safety of current light water reactors, it is necessary to clarify the two-phase flow behavior in the subchannels at the stagnant flow condition. So, the bubbly flow data around a simulated fuel rod were obtained experimentally at the stagnant flow condition. A wire-mesh sensor was used to obtain a detailed two-dimensional void fraction distribution around the simulated spacer and fuel rod. As a result of this research, the bubbly behavior around the simulated spacer and fuel rod was qualitatively revealed and also bubble dynamics in the sub-channels at the conditions of forced convective and stagnant flows were evaluated. The present experimental data are very useful for verifying the detailed three-dimensional two-phase flow analysis codes.

Hydrodynamics of two-phase flow in a rod bundle under cross-flow condition

2016 ◽  
Vol 91 ◽  
pp. 206-214 ◽  
Author(s):  
W.X. Tian ◽  
K. Zhang ◽  
Y.D. Hou ◽  
Y.P. Zhang ◽  
S.Z. Qiu ◽  
...  
Keyword(s):  
Flow Condition ◽  
Two Phase Flow ◽  
Cross Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Rod Bundle

scholarly journals Experimental Investigations on the Inner Flow Behavior of Centrifugal Pumps under Inlet Air-Water Two-Phase Conditions

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4377 ◽  
Author(s):  
Si ◽  
Zhang ◽  
Bois ◽  
Zhang ◽  
Cui ◽  
...  
Keyword(s):  
Two Phase Flow ◽  
Flow Behavior ◽  
Bubbly Flow ◽  
Performance Degradation ◽  
Phase Flow ◽  
Centrifugal Pumps ◽  
Two Phase ◽  
Impeller Blade ◽  
Pump Performance ◽  
Starting Point

Centrifugal pumps are widely used and are known to be sensitive to inlet air-water two-phase flow conditions. The pump performance degradation mainly depends on the changes in the two-phase flow behavior inside the pump. In the present paper, experimental overall pump performance tests were performed for two different rotational speeds and several inlet air void fractions (αi) up to pump shut-off condition. Visualizations were also performed on the flow patterns of a whole impeller passage and the volute tongue area to physically understand pump performance degradation. The results showed that liquid flow modification does not follow head modification as described by affinity laws, which are only valid for homogeneous bubbly flow regimes. Three-dimensional effects were more pronounced when inlet void fraction increased up to 3%. Bubbly flow with low mean velocities were observed close to the volute tongue for all αi, and returned back to the impeller blade passages. The starting point of pump break down was related to a strong inward reverse flow that occurred in the vicinity of the shroud gap between the impeller and volute tongue area.

Proposal of the Estimation Equation of Flow Accelerated Corrosion Under Water-Steam Two-Phase Flow

2013 ◽  
Author(s):  
Masaaki Satake ◽  
Kimitoshi Yoneda ◽  
Ryo Morita ◽  
Fumio Inada
Keyword(s):  
Flow Condition ◽  
Two Phase Flow ◽  
Pipe Wall ◽  
Prediction Equation ◽  
Phase Flow ◽  
Two Phase ◽  
Accelerated Corrosion ◽  
Water Steam ◽  
Flow Accelerated Corrosion ◽  
Thinning Rate

Flow accelerated corrosion (FAC) is one of the pipe wall thinning phenomena. There are a few prediction equations for FAC under the two-phase flow condition, but their accuracy is uncertain. In this study, these equations are summarized. A new prediction equation is proposed, in which the liquid film velocity near the wall is taken into account. Also, FAC experiments with water-steam two-phase flow are performed. The thinning rate is predicted by calculation and compared with the experimental value.

3D CFD Simulation of ESP Rotary Gas-Separator Performance Under Two-Phase-Flow Condition

2005 ◽  
Author(s):  
Leonardo Suarez ◽  
Frank Kenyery ◽  
Miguel Azuaje ◽  
Marco Antonio Pena
Keyword(s):  
Flow Condition ◽  
Cfd Simulation ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Gas Separator

Novel Membrane Bioreactor with Gas/Liquid Two-Phase Flow for High-Performance Degradation of Phenol

1998 ◽  
Vol 14 (5) ◽  
pp. 680-688 ◽  
Author(s):  
D. Leonard ◽  
M. Mercier-Bonin ◽  
N.D. Lindley ◽  
C. Lafforgue
Keyword(s):  
High Performance ◽  
Membrane Bioreactor ◽  
Two Phase Flow ◽  
Performance Degradation ◽  
Phase Flow ◽  
Two Phase
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