为揭示烟气轮机盘腔的冷却机理,分析其内的流动与换热特性,探究冷却蒸汽流量对轮盘温度分布以及烟机总体性能的影响,本文以YL14000C烟气轮机为研究对象,建立了烟气轮机的流热耦合分析模型,获得了其盘腔内流场和温度场,分析了不同蒸汽量对盘腔温度、轮盘温度和烟气轮机气动性能的影响规律。结果表明：冷却蒸汽在输送管弯头处诱发出一对回转涡,经喷嘴后演化为更大的流动分离,并在盘腔轴心处不断受到挤压和拉伸。冷却蒸汽冲击轮盘后,在旋转作用下沿径向扩散,其冷却效果随蒸汽流量的增加而增强。轮盘温度降幅100 ℃左右,且相较于无蒸汽冷却,在距轴心0.3 m处出现最大温度降幅。盘腔中冷却蒸汽和密封蒸汽流量的增加对烟气轮机的气动影响不大,在工程实践中可以不用考虑其影响,针对YL14000C的烟气轮机,500 kg/h的蒸汽量足够保证其安全运行。本文研究结果对于烟气轮机盘腔冷却、盘腔密封设计、冷却蒸汽流量选择以及轮盘温度监测提供了重要的参考。

To reveal the cooling mechanism in the disk cavity of flue gas turbines, analyze its internal flow and heat transfer characteristics, and explore the influence of cooling steam flow rates on the temperature distribution of the disk and overall performance of flue gas turbines, the fluid-thermal-structural coupling model of YL14000C flue gas turbine is set up to obtain the flow field and temperature field in the rotor-stator disk cavity. The rules of different steam flow rates on the disk cavity, disk temperature, and aerodynamic performance are analyzed in this paper. The results show that cooling steam induces a pair of convective vortexes at the elbow of the pipeline, which evolves into a larger flow separation after passing through the nozzle and is continuously squeezed and stretched at the axis of the rotor-stator disk cavity. After cooling steam impinges the disk, it diffuses along the radial direction under the action of disk rotation, and its cooling effect is enhanced with the increase of steam flow rate. The temperature of the disk decreases by about 100 ℃, and the maximum temperature decrease occurs at 0.3 m from the axis compared with no steam cooling. The increase in flow rates of cooling steam and sealing steam in the rotor-stator disk cavity has little effect on the aerodynamics of flue gas turbines, whose effect can be ignored in engineering practice. For YL14000C flue gas turbine, steam rate of 500 kg/h is enough to ensure its safe operation. The results of this paper provide an important reference for rotor-stator disk cavity cooling in flue gas turbines, its sealing structural design, the selection of cooling steam flow rate, and the monitoring of disk temperature.

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