双悬臂轴系结构通过临界转速时振动实验研究

Vibration of double-cantilever shafting structure passing through critical speed

膨胀机和压缩机是压缩空气储能(CAES)系统的关键部件。为满足其变工况、低功耗等要求,中小型机组多采用双悬臂轴系结构,但双悬臂结构振动情况复杂,振动问题直接影响其运行稳定和运行安全,而当前对其研究还不够充分,基于此开展了针对双悬臂轴系结构振动特性的实验研究。重点分析了双悬臂轴系中高速轴的振动幅值曲线、振动频谱、伯德图和振动能量分布频谱图等,确定了该转子的临界转速,并探究了通过临界转速时升速连续性、升速时间等对其振幅的影响。结果表明,本研究双悬臂实验件高速轴临界转速约为14200 r/min,临界转速前共振区域约为临界转速(14200 r/min)的15%,临界转速后共振区域约为临界转速9%。接近临界转速时其他倍频增长幅度均在2μm以下,不及一倍频增长幅度的5%。升速过程连续性对通过临界转速时的振幅有一定影响:尽管“阶梯型”升速方案通过临界转速时的升速率更快,但是由于其在临界转速附近有停留,造成了振动能量累计,因此使振动峰值增加。通过临界转速时,振动峰值会随着提速时间的延长而近似线性增加,当提速时间从20 s延长到60 s时,振幅提升了约20%。

Expander and compressor are the important components of compressed-air energy storage(CAES)systems.To meet the requirements of off-design and low power consumption,the double cantilever shafting structure is used often.However,the vibration of the double cantilever shafting structure is prominent,whereas there are insufficient studies on it,and the related technology is mostly controlled by foreign giants.Based on this,herein,an experimental study of the vibration of the double cantilever shafting structure was conducted.By several speed-up-and-down experiments,the vibration amplitude curve,vibration spectrum,Bode diagram,and vibration energy distribution spectrum of high-speed shafts are analyzed and the critical speed of the rotor is determined.The influence of speed-up continuity and time on the amplitude through the critical speed is then explored.The results show a critical speed of 14200 r/min for the high-speed shaft of the double-cantilever test piece.The resonance region below the critical speed is about 15%,and that beyond the critical speed is about 9%.When the speed is close to the critical value,the increasing range of other frequencies is 2μm,which is less than 5%of the fundamental frequency increase.Through the critical speed,the speed-increasing continuity has an impact on the amplitude.This study presents two types of speed-increasing schemes.Although the acceleration of scheme 2 is faster when passing through the critical speed,the vibration energy accumulates as it is close to the critical speed,making the vibration peak of scheme 2 larger than that of scheme 1.Through the critical speed,the vibration peak increases approximately linearly with an increase in the speed-increasing time.When the speed-increasing time is increased from 20 to 60 s,the amplitude increases by about 20%.