涡轮机叶片同步振动参数辨识方法研究(实验研究)

Tests for synchronous vibration parametric identification method of a turbine's blades

为满足工程应用环境中用尽可能少的传感器和更紧凑的安装空间中实现叶片振动的精确测量,在叶尖定时测量方法的基础上,提出并实验研究了基于变速扫频拟合和辅助参数全局自回归法(GARIV法)相结合来辨识叶片同步振动时的振动参数。建立了高速直叶片实验台(最高转速45 000 r/min,叶尖线速度322.8 m/s)。在实验研究过程中,完成了叶片同步振动的参数辨识(中心频率、振动最大幅值、相位、振动恒偏量和倍频值),准确绘制出安装6个磁铁激励下的叶片部分振动坎贝尔图。同时对不同激励个数时叶片部分谐振动做了实验研究和分析。通过对比叶片的预应力模态计算结果和实验辨识结果,两者偏差小于6%。该方法可为叶片故障预警、动应力非接触测量提供技术途径。

Accurate measurement of blade vibration using as few as possible sensors and more compact installation space is indispensable for engineering applications. Based on the measurement technique of BTT,the combination of the rotating speed-varying sweep frequency fitting method and GARIV one was proposed and tested to identify a turbine＇s blades synchronous vibration parameters here. A high-speed straight blade test rig was established（ the maximum rotating speed is 45 000 r/min,and the blade tip velocity is 322. 8 m/s）. In tests,the parametric identification of blade synchronous vibration was conducted and Campbell diagram of blade vibration was correctly plotted under the excitation of six magnets. Furthermore,tests and analyses of blade harmonic vibration under different numbers of excitation were done.Through comparison,it was shown that the maximum error between the calculation results of blade＇s dynamic stress modes and the corresponding test ones is less than 6%. This method provided a technical way for blade fault early warming and dynamic stress non-contact measurement.