Thermal Hydraulic Flow Oscillation Characteristics in Multiformed Channels under Natural Circulation and Low-Pressure Conditions
Thermal Hydraulic Flow Oscillation Characteristics in Multiformed Channels under Natural Circulation and Low-Pressure Conditions
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DOI：
10.1080/18811248.2008.9711425
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发表时间：
2008-02
影响因子：
1.2
通讯作者：
N. Watanabe;M. Aritomi;H. Kikura
中科院分区：
文献类型：
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作者：
N. Watanabe;M. Aritomi;H. Kikura
对自然循环条件下垂直组合通道内的热工水力不稳定性进行了实验研究。多组合通道由两部分组成;安装在下游的非加热单通道部分和安装在上游的加热平行通道部分。每个通道段的长度可以改变，以研究流动振荡特性的不稳定性。根据各通道长度比的不同，平行通道段的水流振荡模式大致可分为同相（自然循环振荡）、异相（间歇泉、密度波振荡）和中间相3种类型。本研究的目的是通过实验阐明这些流动振荡的传输机制。根据输入热条件的不同，间歇泉可进一步分为格里菲斯型和有富型。特别是在单段长度与平行段长度基本相等的情况下，可以观察到中间相流的振荡现象。中间相流振荡基本上是由于并联通道内压力波动引起的异相流振荡，但由于单通道内的静压头波动，振荡范围在一定宽度内周期性地增大或减小。
Thermal hydraulic instabilities in vertical multicombined channels under natural circulation conditions have been experimentally investigated. The multicombined channels consist of two parts; a nonheated single-channel section installed downstream and a heated parallel-channel section installed upstream. The length of each channel section could be varied to investigate the flow oscillation characteristics of the instabilities. The flow oscillation modes at the parallel-channel section could be roughly classified into three different types according to the length ratio of each channel, such as in-phase (natural circulation oscillation), out-of-phase (geysering, density wave oscillation), and intermediate-phase. The objective of this study is to experimentally clarify the transport mechanisms of those flow oscillations. The resulting geysering could be further classified into Griffith's type and Aritomi's type according to the difference in input thermal conditions. Especially in case that the length of the single section was almost equal to that of the parallel section, the intermediate-phase flow oscillation was observed. The intermediate-phase flow oscillation was basically the out-of-phase flow oscillation due to the pressure fluctuation in the parallel channels, but the range of the flow oscillation periodically increased or decreased in a certain width due to the hydrostatic head fluctuation in the single channel.