铅铋合金冷却反应堆内气泡提升泵提升自然循环能力的理论研究

液态金属冷却核反应堆采用气泡提升泵的概念设计来提升堆芯自然循环能力。液态金属和惰性气体两相流动特性显著影响自然循环能力和系统安全性。本工作对铅铋合金冷却反应堆中气泡提升泵提升自然循环能力进行数值模拟研究。基于漂移流模型，采用空泡份额预测模型和摩擦压降预测模型分析了气体质量流量、质量含气率、气泡直径、上升管道高度对气泡提升泵提升自然循环能力的影响。结果表明：泡状流区域中，对于给定的气体质量流量，随着充入气泡直径减小，自然循环能力呈增加趋势。在泡状流、弹状流、乳状流和环状流等流型中，随着气体质量流量、质量含气率增加，自然循环能力先增大后减小。随着上升管道高度增加，自然循环流量增大。可见，流动参数显著影响堆芯热工水力特性。现有工作有助于优化带有气泡提升泵的自然循环冷却系统设计。

Research on Enhancement of Natural Circulation Capability in Lead-bismuth Alloy Cooled Reactor by Using Gas-lift Pump

The gas-lift pump has been adopted to enhance the natural circulation capability in the conceptual designs of lead-bismuth alloy cooled reactors such as ADS and LMFR. The natural circulation capability and the system safety have been obviously influenced by the two phase flow characteristics of liquid metal-inert gas. The numerical research was performed to evaluate the natural circulation capability of lead-bismuth alloy cooled ADS with gas-lift pump. Based on the drift-flux flow model, void fraction prediction model and frictional pressure drop prediction model were adopted in the numerical simulation. The effects of the gas mass flow rate, the gas quality, the bubble diameter and the height of rising pipe on natural circulation capability of gas-lift pump were analyzed. The results show that in bubbly flow pattern, for a fixed value of gas mass flow rate, the natural circulation capability increases with the decrease of the bubble diameter. In the bubbly flow, slug flow, churn flow and annular flow patterns, with the gas mass flow rate and the gas quality increase, the natural circulation capability increases initially and then decreases. As the height of rising pipe increases, the natural circulation flow rate goes up. The flow parameters influence the thermal hydraulic characteristics of the reactor core significantly. Therefore, in practical engineering application, the gas mass flow rate, gas quality, bubble diameter and rising pipe height are very important parameters for the design of gas-lift pump systems. The present work is helpful for optimizing the design of the natural circulation cooling system by gas-lift pump.