Characteristics of Parallel and Countercurrent Flooding Instability of Annular Flow in Rod Bundle Channel
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摘要:
开展堆芯流动单元内两相逆流行为的实验研究，能为不同形态反应堆系统的顺利运行和应急处理提供足够的理论支撑。本研究对3×3棒束通道环状流中并流-逆流不稳定性的携带行为、流动参数特性和形成机理进行了分析。结果表明，一个携带周期由携带上行起始区域、完全上升环流区域和整体下行区域组成。实验工况根据Wallis判别式判断处于携带状态，根据Zapke和Alekseev判别式的预测结果则处于携带和不能携带的转换线上。当压差达到局部最大值时，高速摄影捕捉到上行起始点；当压差达到局部最小值时，高速摄影拍摄到下行起始点。当液相流速低于0.1 m/s时，整体周期长度并无明显变化；当液相折算速度在0.1～0.3 m/s范围内，整体周期随气相折算速度的增加而减小，上行与下行的时间比值变化较小，液相折算速度高于0.3 m/s时该比值则随气相折算速度的增大而增加。当液相流速低于0.2 m/s时，携带起始混流上升速度高于气相折算速度；当液相流速逐渐增加，携带起始混流上升速度高于气相折算速度的量逐渐减小；当液相折算速度高于0.2 m/s，在高气相折算速度条件下携带起始混流上升速度低于气相折算速度。发生并流-逆流不稳定性的原因是在不同区域内气芯变化的携带力和液相重力的周期性起主导作用。
Abstract:Carrying out the experimental researches on the two-phase countercurrent behaviors in the flow unit of reactor core can provide sufficient theoretical supports for the smooth operation and emergency treatment of different forms of the reactor systems. In this research, the flooding phenomenon, the characteristics of flow parameters and formation mechanisms of parallel and countercurrent flooding instability of annular flow in rod bundle channel were analyzed, and the result indicates that one flooding cycle could be divided into the onset flooding region, the full flooding region and the whole liquid phase downstream region. The experimental conditions where the flow instability appeared in the rod bundle structure are in the flooding state according to the criterion from Wallis, but on the conversion line of flooding and not flooding state according to the criterion from Zapke and Alekseev. The experimental pressure drop changing with time was compared to the instability behaviors of annular flow, and the result shows that when the pressure drop reaches a local maximum, the high-speed photography captures the starting point of onset flooding region, and when the pressure difference reaches a local minimum, the starting point of whole liquid phase downstream region is seen in the field of view. According to the high-speed photographic image data processing, the parallel flow time, the countercurrent flow time and the overall cycle time were acquired and analyzed. When the liquid phase flow rate is lower than 0.1 m/s, the overall cycle time does not change significantly, and the parallel flow time is lower than the countercurrent flow time. When the liquid superficial velocity is within the range of 0.1-0.3 m/s, the overall cycle time decreases with the increasing gas superficial velocity, and the time ratio of the parallel and countercurrent flow time changes little. When the liquid superficial velocity is higher than 0.3 m/s, the time ratio increases with the increasing gas superficial velocity. The study on the micelle velocity for onset-flooding shows that when the liquid superficial velocity is lower than 0.2 m/s, the micelle velocity for onset-flooding is higher than the gas velocity. The value with which the micelle velocity for onset-flooding is higher than gas superficial velocity decreases gradually with the increasing liquid velocity. At some conditions with high gas velocity, the micelle velocity for onset-flooding is lower than the gas superficial velocity when the liquid superficial velocity is higher than 0.2 m/s. The formation mechanisms of parallel and countercurrent flooding instability depend upon the changing force of gas core and the effect of liquid gravity in different flooding regions.
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Keywords:
- rod bundle channel ,
- annular flow ,
- flow instability ,
- countercurrent flow
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图 2 通道结构与高速摄影系统示意图
a——俯视图；b——侧视图
Figure 2. Schematic diagram of rod bundle channel structure and high-speed photography system
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图 5 棒束通道中环状流动不稳定性行为分析
a——携带起始区域；b——完全上升环流区域；c——整体下行区域；d——下一周期携带起始区域
Figure 5. Analysis of annular flow instability in rod bundle channel
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图 6 实验气液工况与4个携带经验式结果比较
Figure 6. Results comparison of experimental conditionswith predictions of four flooding formulas
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图 7 周期性携带图像数据与相对压差时域图的比较
Figure 7. Comparison of periodic flooding image data with relative pressure drop at same time
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图 8 不同流动工况上行-下行时间占比
Figure 8. Proportion of time for upward-downward flow time in different flow conditions
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[1] MA Youfu, ZENG S, SHAO J, et al. An experimental study on gas-liquid two-phase countercurrent flow limitations of vertical pipes[J]. Experimental Thermal and Fluid Science, 2023, 141: 110789. doi: 10.1016/j.expthermflusci.2022.110789
[2] 李希川. 竖直窄矩形流道液泛特性研究[D]. 哈尔滨: 哈尔滨工程大学, 2013. [3] 潘良明, 朱隆祥, 万洁, 等. 轻水堆两相流机理研究的若干关键问题、现状与发展前沿[J]. 原子能科学技术, 2022, 56(8): 1483-1498. doi: 10.7538/yzk.2022.youxian.0411 PAN Liangming, ZHU Longxiang, WAN Jie, et al. Challenge, state-of-art and future of two-phase flow in light-water nuclear reactor[J]. Atomic Energy Science and Technology, 2022, 56(8): 1483-1498(in Chinese). doi: 10.7538/yzk.2022.youxian.0411
[4] WALLIS G. Flooding velocities for air and water in vertical tubes[R]. United Kingdom: United Kingdom Atomic Energy Authority, 1961.
[5] KUTATELADZE S, SOROKIN Y. The hydrodynamic stability of vapour-liquid systems[M]. [S. l.]: [s. n.], 1969.
[6] ZAPKE A, KROGER D. Countercurrent gas-liquid flow in inclined and vertical ducts—Ⅱ: The validity of the Froude-Ohnesorge number correlation for flooding[J]. International Journal of Multiphase Flow, 2000, 26(9): 1457-1468. doi: 10.1016/S0301-9322(99)00098-1
[7] ALEKSEEV V, POBEREZKIN A, GERASIMOV P. Determination of flooding rages in regular packings[J]. Heat transfer/Soviet Research, 1972, 4: 159-163.
[8] 阎昌琪, 黄渭堂, 王文祥, 等. 竖管内淹没及其消失滞后问题的研究[J]. 核科学与工程, 1994, 14(1): 34-41. YAN Changqi, HUANG Weitang, WANG Wenxiang, et al. Study on flooding and hysteresis of deflooding in vertical tubes[J]. Chinese Journal of Nuclear Science and Engineering, 1994, 14(1): 34-41(in Chinese).
[9] 阎昌琪, 孙福泰, 孙仲宁. 管径和气体入口条件对淹没过程的影响[J]. 核动力工程, 1993, 14(3): 238-243. YAN Changqi, SUN Futai, SUN Zhongning. Effects of diameter and air inlet on flooding[J]. Nuclear Power Engineering, 1993, 14(3): 238-243(in Chinese).
[10] VIJAYAN M, JAYANTI S, BALAKRISHNAN A. Effect of tube diameter on flooding[J]. International Journal of Multiphase Flow, 2001, 27(5): 797-816. doi: 10.1016/S0301-9322(00)00045-8
[11] 金光远, 赵珂欣, 王睿, 等. 窄矩形通道内环状流周期性携带特性研究[J]. 原子能科学技术, 2023, 57(8): 1553-1560. JIN Guangyuan, ZHAO Kexin, WANG Rui, et al. Periodic flooding characteristics of annular flow in narrow rectangular duct[J]. Atomic Energy Science and Technology, 2023, 57(8): 1553-1560(in Chinese).
[12] LIU H, HIBIKI T. Flow regime transition criteria for upward two-phase flow in vertical rod bundles[J]. International Journal of Heat and Mass Transfer, 2017, 108: 423-433. doi: 10.1016/j.ijheatmasstransfer.2016.12.029
[13] HAN X, SHEN X, YAMAMOTO T, et al. Flow regime and void fraction predictions in vertical rod bundle flow channels [J]. International Journal of Heat and Mass Transfer, 2021, 178: 121637. doi: 10.1016/j.ijheatmasstransfer.2021.121637
[14] 周云龙, 尹洪梅. 棒束通道气液两相流流型识别及动力学特性分析[J]. 原子能科学技术, 2017, 51(5): 851-857. ZHOU Yunlong, YIN Hongmei. Flow pattern identification and dynamics characteristics of gas-liquid two-phase flow in rod bundle channel[J]. Atomic Energy Science and Technology, 2017, 51(5): 851-857(in Chinese).
[15] KAMEI A, HOSOKAWA S, TOMIYAMA A, et al. Void fraction in a four by four rod bundle under a stagnant condition[J]. Journal of Power and Energy Systems, 2010, 4(2): 315-326. doi: 10.1299/jpes.4.315
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