湿蒸汽流场下介入式探针振动数值模拟

Numerical simulation for vibration of interferometric probe in wet steam flow field

介入式探针在汽轮机末级与湿蒸汽流场相互影响,采用双向流固耦合技术对该三元流动问题进行数值分析,研究探针在湿蒸汽流场下的受力情况和振动特性.利用Workbench平台搭建流固耦合模型,采用基于湍流剪应力输运的k-ω模型以提高计算精度.计算结果表明:探针在X、Y、Z方向的振动周期略有波动,最大振幅分别为0.28 mm、4.75和5.50μm.由于光学探针结构特殊,探针前端测量区域受到压差作用力很小,前端的形变量增长率有所降低.在振动过程中,探针背流方向约2/3探针长度处应力值最大,该值远低于探针材料的许用应力,且在计算工况下不会引发共振效应.

The bidirectional fluid solid coupling technique was adopted to analyze the three-element flow problem that the interferometric probe interacts with the wet steam flow field at the end stage of the steam turbine. The vibration characteristics and stress of the probe under wet steam flow field were studied. The fluid solid coupling model was built by using Workbench platform. The k-ω model based on turbulent shear stress transport was used to improve calculation accuracy. Results show that the vibration period of the three directions X, Y and Z of probe fluctuate slightly. The oscillation amplitudes in directions X, Y and Z were 0.28 mm, 4.75 μm and 5.50 μm, respectively. Due to the special structure of the optical probe, the pressure differential force acting on the tip of the probe is very small, leading to a decrease in the growth rate of the shape variable at the front end. During probe vibration, the maximum stress position of the probe is about 2/3 of the point in the direction of back flow of the probe, the maximum stress is far below the allowable stress of the probe material, and the resonance effect is not induced in the calculation condition.