Numerical simulation of wet steam non-equilibrium condensing flow in cascade passage

doi:10.11949/j.issn.0438-1157.20151614

Abstract

Abstract:

Subcooled degree is the direct drive potential of condensing phenomena happening and developing. The nucleation process of cascade passage sharply occurs in a narrow flow section. Water droplets distribution is affected by boundary layers and wakes. Due to the condensing parameters distribution steep and sensitive, high resolution second-order TVD scheme and time-marching technique were adopted in numerical algorithm. Using numerical algorithm, the condensing parameter distributions was calculated and compared with measured data to verify the accuracy of the numerical algorithm. Basic physical phenomena of non-equilibrium condensing flow and the influence of inlet subcooled degree on the homogenous nucleation were examined. Varying pattern of pressure, nucleation rate, droplets number, droplets radius and wetness were investigated. It was found that the inlet subcooled degree had a significant influence on non-equilibrium phase change in transonic condensing flow.

Key words: wet steam, cascade passage, transonic, two-phase flow, condensation, thermodynamics

摘要：

过冷度是各种凝结现象产生、发展的直接驱动力,叶栅通道内湿蒸汽成核过程通常集中在喉部下游很窄的区域内,水滴数目和水滴半径分布则受到边界层和尾迹影响。针对叶栅通道内跨音速非平衡凝结流动参数分布陡峭、变化敏感的特点,采用具有较好激波捕获效果的高分辨率二阶TVD格式进行离散。利用时间推进法对控制方程进行求解,建立了凝结流动的数值解法,模拟与实验结果相吻合,验证了模型的准确性。研究了叶栅通道内非平衡凝结流动的基本物理现象,讨论了进口过冷度对凝结特性的影响,归纳了叶栅通道内压力、成核率、水滴数、水滴半径、蒸汽湿度的变化规律。研究表明:进口过冷度对非平衡凝结流动特性有重要影响。

关键词: 湿蒸汽, 叶栅通道, 跨音速, 两相流, 凝结, 热力学

CLC Number:

O354

HAN Zhonghe, HAN Xu, LI Hengfan. Numerical simulation of wet steam non-equilibrium condensing flow in cascade passage[J]. CIESC Journal, 2016, 67(5): 1806-1813.

韩中合, 韩旭, 李恒凡. 叶栅通道内湿蒸汽非平衡凝结流动的数值模拟[J]. 化工学报, 2016, 67(5): 1806-1813.

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