共查询到18条相似文献,搜索用时 156 毫秒
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自发凝结流动数值模拟方法及其在Laval喷管中的应用 总被引:3,自引:0,他引:3
本文对存在自发凝结的湿蒸汽两相流动建立了完全欧拉坐标系统下的数理模型。采用考虑了真实流体性质的 LU-SGS-GE隐式时间推进算法和改良型高精度、高分辨率MuSCL TVD差分格式求解存在自发凝结的汽液两相流动控制方程组。文中水及水蒸汽性质数据全部取自IAPWS-IF97国际标准公式。对某Laval缩放喷管内的湿蒸汽自发凝结流动的数值模拟结果表明,本文所采用的数理模型及计算方法是有效和可靠的。 相似文献
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基于存在自发凝结的湿蒸汽两相流动,开发了基于汽液两相双流体模型和k-ε-k_p湍流模型的计算方法,并对喷管和二维叶栅进行数值验证,结果表明本文所开发的方法具有较高的可靠性。对某汽轮机末级除湿静叶考虑除湿槽结构的二维流场进行了数值研究,指出在叶片表面开设除湿槽结构,能够显著影响涡轮叶栅内的非平衡凝结流动。由于除湿槽对水滴的抽吸作用使得叶栅内成核率峰值降低,且变化幅度减小,因此成核过程更为稳定。除湿槽结构使得叶栅内部大水滴数目减少,尾迹区水滴平均半径减小,叶栅出口湿度下降。 相似文献
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引入水蒸气非平衡相变的动力学模型,并在水蒸气真实物性的基础上,建立了水蒸气超声速非平衡流动的守恒型数值计算模型,采用对激波捕捉具有高精度和高分辨率的Roe-FDS格式,数值捕捉了水蒸气超声速流动中的非平衡相变与凝结激波。以非平衡相变中液相质量增长率为基准,将非平衡凝结相变引发的凝结激波划分为凝结激波起始发生区、凝结激波交汇区和凝结激波消退区三个区域,分析了凝结激波的形成机理,得到了凝结激波发生及发展的"X"型分布特征,并归纳了凝结激波的分区物理特性和热力学特性。 相似文献
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汽轮机湿蒸汽级中凝结流动的三维数值分析 总被引:1,自引:0,他引:1
对一台凝汽式汽轮机低压末三级中的湿蒸汽自发凝结流动进行了三维数值分析,并与忽略自发凝结影响的流动计算结果进行了比较。结果表明,自发凝结流动中,湿蒸汽级组内焓降在各级之间的分配、各级反动度、级的工作压力范围、叶栅出口气流角和出口气流速度发生明显变化。各湿蒸汽级处于“变工况”运行状态,部分湿蒸汽级内流动状况显著变差,并导致叶片强度与振动方面安全性降低。除非平衡凝结损失外,凝结导致湿蒸汽透平级“变工况”运行是湿蒸汽级效率降低的重要原因。 相似文献
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The article presents research on a wet steam transonic flow in a Laval half-nozzle with a shock wave. The motivation for this research was to investigate the shock wave/liquid phase interaction in the transonic wet steam flow. This phenomenon is responsible for the lack of good correspondence between experimental data and computational fluid dynamics results. For the tests, the geometry of the half-arc nozzle was used. The shock wave formation at the divergent section of the nozzle is caused by too high back-pressure. The observed instabilities in the flow are mainly initiated by the shock wave/liquid film (boundary layer) interaction. The numerical calculations were compared with experimental results with respect to the static pressure distribution along the nozzle. 相似文献
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Massive droplets can be generated to form two-phase flow in steam turbines, leading to erosion issues to the blades and reduces the reliability of the components. A condensing two-phase flow model was developed to assess the flow structure and loss considering the nonequilibrium condensation phenomenon due to the high expansion behaviour in the transonic flow in linear blade cascades. A novel dehumidification strategy was proposed by introducing turbulent disturbances on the suction side. The results show that the Wilson point of the nonequilibrium condensation process was delayed by increasing the inlet superheated level at the entrance of the blade cascade. With an increase in the inlet superheated level of 25 K, the liquid fraction and condensation loss significantly reduced by 79% and 73%, respectively. The newly designed turbine blades not only remarkably kept the liquid phase region away from the blade walls but also significantly reduced 28.1% averaged liquid fraction and 47.5% condensation loss compared to the original geometry. The results provide an insight to understand the formation and evaporation of the condensed droplets inside steam turbines. 相似文献
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