Numerical Simulation of Condensation in Supercritical CO2 Compressor Based on Equilibrium Condensation Model
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摘要: 超临界二氧化碳（sCO2）布雷顿循环是第四代核反应堆能量转换系统主要解决方案之一，实际运行中，压缩机内sCO2可能发生凝结，导致效率降低，运行稳定性受到影响。本文结合Span-Wagner物性模型，建立了sCO2的平衡冷凝数值模型，对sCO2压缩机进行数值模拟，分析了sCO2冷凝的主要区域、成因及影响。结果表明，sCO2的凝结主要受流速影响，发生于压缩机主叶片前缘吸力面的50%叶高以上区域及前缘间隙内近压力面区域，前一区域由sCO2的局部加速所致，后一区域由叶顶间隙泄漏所致；在给定工况下，冷凝区域很小，未扩展到整个通道，冷凝的sCO2很少，未形成两相流，对压缩机运行的影响很小。
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关键词:
- 超临界二氧化碳（sCO2） /
- 离心压缩机 /
- 数值计算 /
- 冷凝
Abstract: Supercritical carbon dioxide (sCO2) Brayton cycle is one of the main solutions of the Generation IV nuclear reactor energy conversion system. During the actual operation, sCO2 in the compressor may condense. As a result, the efficiency is reduced and the operation stability is affected. In this paper, the equilibrium condensation numerical model of sCO2 was established with the Span-Wagner model, and the numerical simulation of the sCO2 compressor was carried out. The main condensation regions, causes and influences of the condensation of sCO2 were analyzed. The results show that the condensation of SCO2 is mainly affected by the flow velocity. The condensation of sCO2 occurs in the area above 50% blade height on the suction surface of the leading edge of the main blade and near the pressure surface in the leading edge gap. The former area is caused by local acceleration of sCO2, and the latter area is caused by tip clearance leakage; Under the given working condition, the condensation area is very small, which does not extend to the whole channel, the condensed sCO2 is very little, and no two-phase flow is formed, which has little influence on the operation of the compressor. -
图 7 流场分析涉及的研究区域图示
ω—叶轮旋转角速度
Figure 7. Illustration of the Study Area Involved in the Flow Field Analysis
图 10 sCO2速度的分布及其对状态的影响
Figure 10. Distribution of sCO2 Velocity and Its Influence on Status
图 11 主叶片表面的静温、静压云图与冷凝区域
Figure 11. Static Temperature, Static Pressure Contour and Condensation Area on the Main Blade Surface
图 12 叶表前缘20%、50%和80%叶高处的速度
Figure 12. Velocities at 20%, 50% and 80% of the Blade Height at the Leading Edge of the Blade Surface
图 14 叶表前缘20%、50%和80%叶高处sCO2密度
Figure 14. sCO2 Density at 20%, 50% and 80% of the Blade Height at the Leading Edge of the Blade Surface
表 1 叶轮几何尺寸信息
Table 1. Impeller Geometry
参数名 参数值 参数名 参数值 主叶片数量 6 叶顶间隙/mm 0.254 分流叶片数量 6 前缘叶厚/mm 0.762 轮毂进口半径/mm 2.54 尾缘叶厚/mm 0.762 轮盖进口半径/mm 9.37 前缘叶高/mm 1.7 出口半径/mm 18.68 前缘几何角 37.13° 轴向长度/mm 15.9 尾缘几何角 −50° 
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