基于平衡冷凝模型的超临界CO_(2)压缩机内部冷凝数值分析

Numerical Simulation of Condensation in Supercritical CO_(2) Compressor Based on Equilibrium Condensation Model

超临界二氧化碳(sCO_(2))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sCO_(2)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sCO_(2)的平衡冷凝数值模型,对sCO_(2)压缩机进行数值模拟,分析了sCO_(2)冷凝的主要区域、成因及影响。结果表明,sCO_(2)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sCO_(2)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sCO_(2)很少,未形成两相流,对压缩机运行的影响很小。

Supercritical carbon dioxide(sCO_(2)) Brayton cycle is one of the main solutions of the Generation IV nuclear reactor energy conversion system.During the actual operation,sCO_(2) 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 sCO_(2) was established with the Span-Wagner model,and the numerical simulation of the sCO_(2) compressor was carried out.The main condensation regions,causes and influences of the condensation of sCO_(2) were analyzed.The results show that the condensation of SCO_(2) is mainly affected by the flow velocity.The condensation of sCO_(2) 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 sCO_(2),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 sCO_(2) is very little,and no two-phase flow is formed,which has little influence on the operation of the compressor.