Nuclear Engineering and Technology
- Volume 31 Issue 6
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- Pages.572-585
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- 1999
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- 1738-5733(pISSN)
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- 2234-358X(eISSN)
Development of a Linear Stability Analysis Model for Vertical Boiling Channels Connecting with Unheated Risers
- Hwang, Dae-Hyun (Korea Atomic Energy Research Institute) ;
- Yoo, Yeon-Jong (Korea Atomic Energy Research Institute) ;
- Zee, Seong-Quun (Korea Atomic Energy Research Institute)
- Published : 1999.12.01
Abstract
The characteristics of two-phase flow instability in a vertical boiling channel connecting with an unheated riser are investigated through the linear stability analysis model. Various two-phase flow models, including thermal non-equilibrium effects, are taken into account for establishing a physical model in the time domain. A classical approach to the frequency response method is adopted for the stability analysis by employing the D-partition method. The adequacy of the linear model is verified by evaluating experimental data at high quality conditions. It reveals that the flow-pattern-dependent drift velocity model enhances the prediction accuracy while the homogeneous equilibrium model shows the most conservative predictions. The characteristics of density wave oscillations under low-power and low-quality conditions are investigated by devising a simple model which accounts for the gravitational and frictional pressure losses along the channel. The necessary conditions for the occurrences of type-I instability and flow excursion are deduced from the one-dimensional D-partition analysis. The parametric effects of some design variables on low quality oscillations are also investigated.