尾桨升降转速自然激励固有频率识别方法研究

Tail Rotor Up and Down Rotate Speed Nature Excitation Modal Frequency Distinguishing Method

以直升机尾桨固有频率识别为研究背景,针对传统激振器激励方法不能识别高于50Hz尾桨频率问题,发展了基于升降转速自然激励的尾桨固有频率识别方法。随着尾桨转速变化,当气动谐波自然激振频率与模态固有频率重合时尾桨出现共振现象。首先通过谐波分析法将载荷时域信号转换到频域;然后结合共振图和共振点判断准则识别共振点;最后将理论与试验共振点的平均偏差用于推算额定转速下的固有频率。尾桨试验表明该方法识别结果可信。

In the background of distinguishing natural frequency of the helicopter tail rotor, in order to solve the problem that traditional exciter excitation method cannot distinguish the frequency of tail rotor beyond 50Hz, a modal frequency distinguish method which based on up and down rotate speed nature excitation was developed. With tail rotor rotate speed changing, resonance phenomenon appeared on the tail rotor when nature exciter frequency of aerodynamic harmonic coincide with modal natural frequency. Firstly, harmonic analysis method was used to transform load signal from time domain to frequency domain . Then resonance spot was distinguished by resonance diagram and resonance spot judge standard. At last modal frequency of rated rotate speed was estimated by average deviation of theory and test resonance spot . Tail rotor test indicated the method recognized result was credible.