Research of two‐phase density wave instability in reactor core channels with rolling motion

2020 ◽  
Vol 44 (9) ◽  
pp. 7323-7341
Author(s):  
Wenxi Tian ◽  
Qiang Lian ◽  
Suizheng Qiu ◽  
G.H. Su
Keyword(s):  
Density Wave ◽  
Reactor Core ◽  
Rolling Motion ◽  
Wave Instability ◽  
Two Phase ◽  
Phase Density

The application of pulsation ratio preprocessing method in researching density wave instability

2018 ◽  
Vol 10 (3) ◽  
pp. 140-145
Author(s):  
Yefei Liu ◽  
Yang Liu ◽  
Xingtuan Yang ◽  
Haijun Jia
Keyword(s):  
Frequency Domain ◽  
Density Wave ◽  
Annular Channel ◽  
Frequency Domain Analysis ◽  
Wave Instability ◽  
Two Phase ◽  
Transform Method ◽  
Modified Method ◽  
Fast Fourier Transform Method ◽  
Dc Component

A modified Fast Fourier Transform method based on the pulsation ratio preprocessing is carried out in this study. When the density wave instability occurs, the method is applied to capture the characteristic signals in the frequency domain. Thus, the stable boundary in two-phase flow can be recognized accurately. In this paper, experiments are conducted in a system based on a narrow annular channel. The method is verified through two groups of experimental data collected in different conditions. The results indicate that the modified method can avoid the problem of DC component spectrum leakage in traditional frequency-domain analysis with the false value interference eliminated. Accordingly, it can improve the accuracy of boundary identification effectively when the instability occurs.

Density Wave Instability of Sodium Boiling Two-phase Flow in a Vertical Annulus at Low Pressure

2003 ◽  
Vol 40 (7) ◽  
pp. 493-500 ◽  
Author(s):  
Suizheng QIU ◽  
Minoru TAKAHASHI ◽  
Dounan JIA ◽  
Guanghui SU
Keyword(s):  
Two Phase Flow ◽  
Density Wave ◽  
Low Pressure ◽  
Phase Flow ◽  
Wave Instability ◽  
Two Phase ◽  
Vertical Annulus

Experimental Study on Density Wave Instability of Sodium Boiling Two-Phase Flow in an Annulus

2002 ◽  
Author(s):  
Suizheng Qiu ◽  
Minoru Takahashi ◽  
Dounan Jia
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Two Phase Flow ◽  
Density Wave ◽  
Inlet Temperature ◽  
Phase Flow ◽  
Wave Instability ◽  
Two Phase ◽  
System Pressure

Experiments of density wave instability in a liquid sodium boiling two-phase flow experiments in an annulus were carried out in the following parameters range: heat flux from 80kW/m2 to 976kW/m2, inlet subcooling from 25.6°C to 226.8°C, mass flow rate from 7.92kg/h to 68.9kg/h, system pressure from 2600Pa to 0.12Mpa. Not only the mechanism of the instability, critical conditions and oscillation period, but also the effects of pressure, mass flow rate and inlet subcooling on the density wave instability were explored experimentally and theoretically. From the experimental data, it was found that the lower the inlet temperature was, the higher the system pressure and the mass flow rate that could result in a more stable boiling two-phase flow were. A correlation for the density wave instability was obtained on from the dimensional analysis for the conservation equations of mass, momentum and energy.

Research on Two-Phase Flow Instability in Evaporator of Refrigeration System

2010 ◽  
Author(s):  
Nan Liang ◽  
Changqing Tian ◽  
Shuangquan Shao
Keyword(s):  
Pressure Drop ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Two Phase Flow ◽  
Density Wave ◽  
Phase Flow ◽  
Constant Mass ◽  
Refrigeration System ◽  
Two Phase

As one kind of fluid machinery related to the two-phase flow, the refrigeration system encounters more problems of instability. It is essential to ensure the stability of the refrigeration systems for the operation and efficiency. This paper presents the experimental investigation on the static and dynamic instability in an evaporator of refrigeration system. The static instability experiments showed that the oscillatory period and swing of the mixture-vapor transition point by observation with a camera through the transparent quartz glass tube at the outlet of the evaporator. The pressure drop versus mass flow rate curves of refrigerant two phase flow in the evaporator were obtained with a negative slope region in addition to two positive slope regions, thus making the flow rate a multi-valued function of the pressure drop. For dynamic instabilities in the evaporation process, three types of oscillations (density wave type, pressure drop type and thermal type) were observed at different mass flow rates and heat fluxes, which can be represented in the pressure drop versus mass flow rate curves. For the dynamic instabilities, density wave oscillations happen when the heat flux is high with the constant mass flow rate. Thermal oscillations happen when the heat flux is correspondingly low with constant mass flow rate. Though the refrigeration system do not have special tank, the accumulator and receiver provide enough compressible volume to induce the pressure drop oscillations. The representation and characteristic of each oscillation type were also analyzed in the paper.

Identification of flow regime and estimation of volume fraction independent of liquid phase density in gas-liquid two-phase flow

2017 ◽  
Vol 98 ◽  
pp. 29-37 ◽  
Author(s):  
G.H. Roshani ◽  
E. Nazemi ◽  
M.M. Roshani
Keyword(s):  
Liquid Phase ◽  
Flow Regime ◽  
Two Phase Flow ◽  
Volume Fraction ◽  
Phase Flow ◽  
Two Phase ◽  
Phase Density
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