烟气轮机盘腔内蒸汽冷却机理与影响特性

To reveal the cooling mechanism of steam in the disk cavity of flue gas turbines, analyze its internal flow and heat transfer characteristics of cooling steam, and explore the influence of cooling steam flow rates on the temperature distribution in the disk cavity and the aerodynamic performance of the flue gas turbines, the fluid-thermal coupling model of YL14000C flue gas turbine was set up to obtain the flow field and temperature field in the disk cavity by numerical simulation method. The influence rules of different steam flow rates on the temperature of the disk cavity and the aerodynamic performance of the flue gas turbine were analyzed. The results show that cooling steam induces a pair of convective vortexes at the elbow of the pipeline, which evolves into the larger flow separation after passing through the nozzle. Then convective vortex are continuously squeezed and stretched at the axis of the 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. After steam cooling, the temperature of the disk is about 100 ℃ lower than that without steam cooling, and the maximum temperature decrease occurs at 0. 3 m from the axis compared with no steam cooling. The increase of cooling steam and sealing steam flow rates in the disk cavity has little effect on the aerodynamic performance of flue gas turbines, which effect can be ignored in engineering practice. For YL14000C flue gas turbine, steam flow rate of 500 kg/h is enough to ensure its safe operation.