新开发的低压末级叶片采用自带冠式整圈自锁阻尼围带、自带凸台式阻尼拉筋的叶片结构形式，为验证并调整叶片的共振频率，使其在考核转速范围内不存在规定节径数的三重点共振，须对其进行动频试验研究。开发了基于WiFi通信的动态应变遥测方法和基于单喷嘴压缩空气射流激振方法的汽轮机叶片动频试验系统。考虑叶片静频和周向均布等因素，在整圈叶片中挑选总数10%的叶片作为被测对象，对应变片采用掩膜定位，对导线采用封胶、蒙皮等工艺，保证测量精度和测点完好率。试验表明：被测叶片三重点共振频率在转速较低时分散度较大，随着转速升高分散度减小；围带切削减薄，降低了围带刚度，改善了接触状况，有利于减小动频分散度。

The newly developed lowpressure last stage blade adopts the structural forms of circumferential selflocking damping shroud with tips and damping tie wire with boss.In order to verify and adjust the resonance frequency of the blades,and ensure that no triple point resonance occurs with the specified nodal diameter within the check speed range,a dynamic frequency test research is necessary.A steam turbine blade dynamic frequency test system,which is based on WiFi communication dynamic strain telemetry and singlenozzle compressed air jet excitation methods,is developed.Considering the factors of static frequency and circumferential uniformity of the blades,10% of the total blades in the entire circle are selected as the measured object.The strain gauges are positioned by masks when they are mounted,and the leads are sealed and skinned for measurement accuracy and test data integrity.The test results show that the triple point resonance frequency of the measured blades has a greater dispersion when the rotation speed is low,and the frequency dispersion decreases as the rotation speed increases; the shroud cutting reduces the stiffness of the shroud,improves the contact state and contributes to the reduction of dynamic frequency dispersion.

TK263.3

杭州市科学技术委员会重大科技创新专项(20172011A02)