窄矩形通道自然循环流动停滞与临界热流密度研究  

Study on natural circulation flow stagnation and critical heat flux in narrow rectangular channel

作　　者：盛程[1] 周涛[1] 张蕾[1] 肖泽军 黄彦平 

机构地区：[1]华北电力大学核热工安全与标准化研究所,北京102206 [2]中核集团核反应堆热工水力技术重点实验室,四川成都610041

出　　处：《核科学与工程》2013年第1期65-75,共11页Nuclear Science and Engineering

基　　金：国家自然科学基金资助(50976033);空泡物理与自然循环国家重点实验室基金(9140C7101030905);华北电力大学"211工程"三期校内面上项目(X10011)

摘　　要：在华北电力大学自然循环实验室进行了自然循环条件下窄矩形通道内的临界热流密度(CHF)实验,对实验中出现的流动停滞及传热恶化现象进行了观察。提出自然循环饱和沸腾条件下,窄矩形通道内的流动停滞-传热恶化发生机理。即自然循环流量漂移发生后会产生流型变迁不稳定,继而造成流量的持续波动,并导致停滞现象,从而使出口附近的液膜层在一定的热流密度下被完全蒸发并引起CHF现象。而窄矩形通道内,由于受间隙尺寸的限制,蒸汽流对加热面上的液膜层产生挤压作用,加热面上液膜层厚度因此会变得较薄,在较小的加热量下便能发生传热恶化。基于机理分析,给出了相应的计算模型。引入了考虑窄通道间隙尺寸效应的无量纲约束数Nconf和反映自然循环流动特点的特征因子C,分别对模型进行了修正。根据实验结果,对计算模型进行了多元回归拟合,并对其准确性进行了验证。通过对实验结果与模型计算值的比较发现,随着通道入口流速和系统压力的增大,CHF均增大;而随着出口干度的增大,CHF会减小。Experiments of critical heat flux （CHF） under natural circulation condition in narrow rectangular channel were conducted in Natural Circulation Laboratory of NorthChina Electric Power University. The phenomena of flow stagnation and heat transfer deterioration were observed during the experiments. The developing mechanism of flow stagnation/ heat transfer deterioration in narrow rectangular channel under saturation condition was proposed. Flow pattern instability would appear when the flow excursion occurred, thus leading to the continuous flow oscillation and flow stagnation. Then the liquid layer near the outlet would completely evaporate under a certain heat condition, and the CHF occurred. While in narrow rectangular channel, the vapor stream could produce extrusion action to the liquid layer on the heating wall due to the limitation caused by gap size, which cause the liquid to become very thin and heat transfer deterioration could happen under a much lower heat flux condition. Based on the mechanistic analysis, a corresponding calculation model was provided. A dimensionless number of constraints and a natural circulation characteristic factor were brought in to optimize the proposed model for the purpose of considering the effects of gap size and circulation mode in the model respectively. The multiple regressions were applied to the calculation model according to the experimental results, and the accuracy of which was validated. The comparison between experimental results and model calculation values indicated that CHF would increase with the inlet velocity and system pressure increased, and would decrease with the outlet quality increased.

关 键 词：窄矩形通道 自然循环 流动停滞 临界热流密度 

分 类 号：TK124[动力工程及工程热物理—工程热物理]