Experimental Study on Liquid Film Dryout Under Oscillatory Flow Conditions
Experimental Study on Liquid Film Dryout Under Oscillatory Flow Conditions
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DOI：
10.1115/icone17-75400
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
Yosuke Yamagoe;T. Goto;T. Okawa
中科院分区：
文献类型：
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作者：
Yosuke Yamagoe;T. Goto;T. Okawa
采用高功率密度堆芯是提高先进沸水反应堆经济性的有效途径之一。然而，众所周知，在沸腾的两相流中，功率密度的增加通常会降低导致意外流动不稳定的裕度。因此，在开发高功率密度堆芯沸水反应堆时，即使在冷却剂流量不稳定的情况下，预测沸腾转变的发生也是必不可少的。本文采用正弦振荡法对进气质量流进行了振荡，并对流动振荡条件下的临界热流密度进行了实验测量。结果表明，临界热流密度随振荡幅度和振荡周期的增大而单调减小。这些结果与之前研究人员报告的实验数据一致。然后提出了一个简单的理论来估算振荡流动条件下的临界热流密度。考虑到在先进沸水反应堆中的应用，临界热流条件的触发机理应是高蒸汽品质环状两相流区的液膜干涸。在流动振荡条件下，由于入口质量流量的时变，液膜上可能会形成长波。假定沸腾通道内的波动演化对液膜局部干涸的发生有影响，将现有的非线性波动理论应用于流动振荡条件下的临界热流密度估算。结果表明，在振荡条件下测得的临界热流密度与所提出的理论吻合较好。版权所有*2009，ASME
The use of high power density core is one of the promising ways to improve economic efficiency of advanced boiling water reactors. It is however known that in boiling two-phase flows, an increase in power density commonly reduces the margin to the onset of unanticipated flow instability. Hence, in the development of a boiling water reactor of high power density core, ability to predict the occurrence of boiling transition is considered indispensable even when the coolant flow rate is not in the steady state. In the present work, sinusoidal oscillation was applied to the inlet mass flux and the experimental measurement of the critical heat flux was carried out under flow oscillation conditions. It was shown that the critical heat flux decreases monotonically with increased values of oscillation amplitude and oscillation period. These results are consistent with experimental data reported by previous investigators. A simple theory was then proposed to estimate the critical heat flux in oscillatory flow condition. Considering the application to the advanced boiling water reactors, the triggering mechanism of the critical heat flux condition is supposed to be the liquid film dryout in annular two-phase flow regime of high vapor quality. Under the flow oscillation condition, it is expected that long waves are formed on a liquid film due to the time variation of inlet mass flux. Assuming that the wave evolution within a boiling channel is influential in the occurrence of the local dryout of a liquid film, an available nonlinear wave theory was applied to the estimation of critical heat flux under the flow oscillation condition. It was demonstrated that the critical heat fluxes measured under the oscillatory conditions agree with the proposed theory fairly well.Copyright © 2009 by ASME