柔性Rushton桨的振动特性

Vibration characteristics of flexible-blade Rushton impeller

为了避免柔性Rushton桨的共振现象,研究搅拌桨的固有频率。采用试验测试的方法,研究该桨在静止及不同转速时的时域特性,并基于快速傅里叶变换法,得到频域特性。结果表明:静止状态下柔性叶片的振动能量主要集中在1~7 Hz的频带上,不同转速时柔性叶片的振动能量主要集中在各自峰值对应的频带上,其中在47~52 Hz的频带上,试验测量的各转速数据均有加速度峰值分布。在转速为2.5 r/s时,加速度幅值明显增大,主振频率等于固有频率2.5 Hz,可判定此时发生共振。因此,通过试验测试得到共振转速的方法,可为柔性桨合理选择转速提供依据。

A natural frequency of a new type of flexible-blade Rushton impeller was studied to avoid a resonance phenomenon.The vibration characteristics of this impeller under stationary and rotating working conditions were experimentally investigated.Frequency domain characteristics were obtained by making Fast Fourier Transformation(FFT)of time domain characteristics.The results showed that a vibration energy of the impeller was mainly concentrated in a frequency band of 1-7 Hz under the stationary state.A vibration energy of a rotating impeller with different speeds was mainly concentrated in a frequency bands corresponding to their respective peaks.Specifically,a peak acceleration distribution of acceleration data was shown in a frequency band of 47-52 Hz.The acceleration amplitude increased significantly at 2.5 r/s,and a main vibration frequency was equal to the natural frequency,which was 2.5 Hz.So it was judged that resonance occured at this time.Therefore,the method of obtaining the resonance rotational speed through the test provided a basis for a reasonable selection of the rotational speed of the flexible-blade impeller.