由于汽轮机内高速凝结流动的复杂性,目前还没有一个得到普遍公认的凝结成核模型,且现有数值模型通常忽略汽液相间滑移.针对叶栅通道内凝结参数分布陡峭、变化敏感的特点,采用既能准确描述可压缩气体跨声速流动又能捕捉参数突跃的双流体数值模型,对汽轮机动叶栅顶部通道内的凝结流动特性进行分析.揭示压比对湿蒸汽非平衡凝结特性的影响,归纳了叶片表面压力、成核率、湿度、水滴数的变化规律.研究表明:各工况压力面的压比计算值与实验数据吻合较好,但吸力面后半段存在一定误差;双流体数值模型适用于过热工况和入口过冷度较小的凝结工况,但当入口过冷度较大时,几乎无法捕捉到凝结激波导致的压力突跃;激波干涉和涡团掺混也会对水滴分布产生较大影响.%Steam turbines are critical power generation equipment in electric power industry. Understanding water vapor condensation flow is important to improve efficiency and safety of steam turbines. Due to complexity of high speed condensation flow in steam turbines, no universally accepted nucleation model is available at present and current numerical models usually neglect vapor-liquid slip. Considered steep distribution and change sensitivity of condensing parameters, a double fluid numerical model of shear stress transport (SST)k-ω-kd two-phase turbulence, which can not only describe transonic flow of compressible gas accurately but also capture parameter jump instantly, was used to analyze condensation flow characteristics in turbine rotor blade tip section. The study revealed influence of pressure ratio on non-equilibrium condensation flow characteristics of wet steams and summarized changing patterns of surface pressure, nucleation rate, humidity, and number of water droplets. Results showed that calculation of pressure ratio at compression surface was in good agreement with experimental data under various operating conditions, although some error was observed in the second half of suction surface. The two fluid numerical model was applicable to both overheating operation and condensations with slight overcooling inlet. But pressure jump caused by condensation shock could hardly be caught for large overcooling inlet. Shock wave interference and vortex mixing had a great influence on distribution of water droplets.
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