弹珠对汽轮机效率及叶片断裂、水蚀的影响

Influence of Water Marbles on Efficiency,Blade Fracture and Water Erosion of Steam Turbines

通过对一台抽汽凝汽式汽轮机组叶片水蚀状况进行分析,提出导致叶片断裂和水蚀的主要原因是由弹珠所引起的"弹珠阻止转子旋转的制动力",它会直接影响汽轮机效率.阐述了由"弹珠"所形成的二次水滴与叶片出汽边处的"水膜"被高速汽流撕裂和破碎所形成的二次水滴的区别.指出利用一定的科学技术手段,改变隔板的结构形式可以有效地减少弹珠的生成数量,减小损耗,减小和抑制"弹珠阻止转子旋转的制动力",从而达到提高机组效率、延长叶片使用寿命的目的.

By analyzing the status of blade fracture and water erosion occurring in an extraction condensing turbine unit, the failure is found to be caused mainly by the braking force from water marbles, which inhibits the rotation of the rotor, and therefore directly affects the efficiency of the steam turbine. The formation mechanism of secondary water droplets from water marbles is compared with that from water films at blade trailing edge torn and broken by high-speed steam flows. It is pointed out that the number of water marbles can be effectively decreased by changing the structure of corresponding baffle plates, so as to reduce the mentioned braking force, economize the energy consumption, and therefore elongate the blade life and raise the unit efficiency.