Analysis of Two-Phase Flow Instability in Multi-Channel System

2014 ◽  
Author(s):  
Genglei Xia ◽  
Minjun Peng ◽  
Du Xue
Keyword(s):  
Two Phase Flow ◽  
Flow Instability ◽  
Saturation Pressure ◽  
Computer Code ◽  
Phase Flow ◽  
Parallel Channel ◽  
Multichannel System ◽  
Two Phase ◽  
Forced Circulation ◽  
Channel System

Ledinegg instability is one of the most important static instabilities for two phase flow system, especially in microchannel systems. In this paper, the force circulation two phase flow instability in vertical multi-channel system is performed by the best estimate system computer code RELAP5. The process and inherent reason of flow instability between multichannel system (FIBM) and flow excursion in forced circulation parallel channel system are analyzed. The effects of main operating parameters related to static onset of flow instability are investigated. Inlet subcooling, inlet restrictor, and saturation pressure are sensitive to the stability of parallel channel system.

Research on Two-Phase Flow Instability in Parallel Multi-Channel Under Rolling Motion Condition

2008 ◽  
Author(s):  
Y. J. Zhang ◽  
G. H. Su ◽  
S. Z. Qiu ◽  
X. B. Yang
Keyword(s):  
Two Phase Flow ◽  
Flow Instability ◽  
Stability Boundary ◽  
Channel Number ◽  
Rolling Motion ◽  
Phase Flow ◽  
Two Phase ◽  
Channel System ◽  
Motion Condition ◽  
High Equilibrium

Two-phase flow instability of the parallel multi-channel system has been studied under rolling motion condition in this paper. Based on the homogeneous flow model with considering the rolling motion condition, the parallel multi-channel model is established by using the control volume integrating method. Gear method is used to solve the system equations. The influences of the inlet and upward sections and the heating power on the flow instability under rolling motion condition have been analyzed. The marginal stability boundary (MSB) under rolling motion condition is obtained and the unstable regions occur in both low and high equilibrium quality regions. The region with low inlet subcooling is also instable. In high equilibrium quality region, the multiplied period phenomenon is found and the chaotic phenomenon appears at the MSB. The oscillation part of mass flow rate (amplitude) may be averaged into other channels so that the influence of rolling motion is weakened. But the stability of multi-channel system is independent of the channel number and the increase of the channel number could only make the amplitude more uniformity in channels.

H225 Two-Phase Flow Dynamics in Parallel-Channel System

2011 ◽  
Vol 2011 (0) ◽  
pp. 377-378
Author(s):  
Takashi NIKAIDO ◽  
Mamoru OZAWA ◽  
Kenso ARITA
Keyword(s):  
Two Phase Flow ◽  
Flow Dynamics ◽  
Phase Flow ◽  
Parallel Channel ◽  
Two Phase ◽  
Channel System

Experiment investigation on two-phase flow instability in a parallel twin-channel system

2010 ◽  
Vol 37 (10) ◽  
pp. 1281-1289 ◽  
Author(s):  
Yun Guo ◽  
Jun Huang ◽  
Genglei Xia ◽  
Heyi Zeng
Keyword(s):  
Two Phase Flow ◽  
Flow Instability ◽  
Phase Flow ◽  
Two Phase ◽  
Channel System

The Research of Flow Instability in Vertical Parallel Natural Circulation Channels Based on Relap5

2013 ◽  
Author(s):  
Jingjing Li ◽  
Tao Zhou ◽  
Mingqiang Song ◽  
Yanping Huang
Keyword(s):  
Two Phase Flow ◽  
Single Channel ◽  
Flow Instability ◽  
Natural Circulation ◽  
Computer Code ◽  
Phase Flow ◽  
Flow Oscillation ◽  
Two Phase ◽  
Best Estimate ◽  
Estimate System

The gas-liquid two phase flow oscillation in vertical parallel natural circulation channels was performed by the best estimate system computer code Relap5. The effects of symmetry and dissymmetry degree of heated power to flow oscillation and the effects of symmetry and dissymmetry throttling to flow oscillation were researched. The results says that when the twin channels under the same conditions of geometry and boundary, the parameters of the twin channel such as flow are the same. So under these conditions the twin channels can be researched as single channel. It is more possible of flow oscillation for the channels under condition of dissymmetry heating. The use of throttling will make the channels more stable, it is more stable when the throttling coefficient increases. With the implement of dissymmetry throttling, the system is possible for out of phase flow oscillation.

Analysis of Two-Phase Flow Instability in Multichannel System

2008 ◽  
Author(s):  
Fu-Yu Zhao ◽  
Su-Xia Hou ◽  
Yun Tai
Keyword(s):  
Characteristic Equation ◽  
Nuclear Reactor ◽  
Two Phase Flow ◽  
Transfer Functions ◽  
Flow Instability ◽  
Oscillation Mode ◽  
Phase Flow ◽  
Multichannel System ◽  
Two Phase ◽  
Oscillation Modes

Two-phase flow instability in parallel multichannels is an important problem that affects operation safety of all large-capacity power boilers and nuclear reactor systems. Occurrence of instabilities and their modes of oscillations can be evaluated by investigating into a characteristic equation, its roots and composing channels transfer functions. It is also shown that a governing matrix is reduced to a diagonal one by using its eigenvalues, the oscillation modes being divided into number of channels separate fundamental modes. Characteristics of each oscillation mode are given by examining corresponding characteristic equations, which are applied for the prediction of oscillation modes of systems composed of a few slightly different channels.

Analysis of Two-Phase Flow Instability for Steam Generator

2008 ◽  
Author(s):  
Su-Xia Hou ◽  
Yun Tai ◽  
Fu-Yu Zhao
Keyword(s):  
Steam Generator ◽  
Nuclear Reactor ◽  
Two Phase Flow ◽  
Flow Instability ◽  
Computer Code ◽  
Frequency Domain Method ◽  
Phase Flow ◽  
Steam Generators ◽  
Two Phase ◽  
The Stability

Two-phase flow instability is an important problem that affects the running of steam generators in nuclear reactor systems. In this paper, two-phase flow instability in parallel channels of a steam generator are analyzed to disclose the mechanism of flow instability by using the frequency domain method. The mathematical expressions of heat transfer and flow for a steam generator are proposed, and the transfer function of the closed-loop system is deduced by using linearization and Laplace transfer. The steam generator’s stability is judged according to Nyquist stability criterion. Depending on this fundamental principal, the computer code is developed to analyze the stability of steam generators. The results displayed two conclusions; firstly, the increase of inlet orifices or mass flow rate enhances the stability of generator steam; secondly, the coupling interactions between channels and their external loop effects on the stability of generator steam are not ignored. The result show that the effects are non-monotonic on the stability of generator steam.

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