Coriolis质量流量传感器内部耦合振动

谐振式科里奥利质量流量计(CMF),依靠测量管路工作在谐振状态产生的科氏力效应实现流体流量的测量.实际的谐振式科里奥利质量流量计工作过程中,普遍存在传感器的外部和内部耦合振动现象,直接影响流量计的稳定性和测量精度.对传感器的外部耦合振动问题,通过增加测量管路直管段、增强传感器固定刚度等措施已得到较好解决;传感器内部耦合振动问题目前尚无完善的理论指导和技术解决方案.结合CMF传感器的工作机理,利用激光测振仪对存在内部耦合振动问题和无内部耦合振动问题的CMF对比测试,进一步证实了传感器内部耦合振动对测量精度的影响,揭示了内部耦合振动对测量管振动的影响相当于在测量管的主振动上叠加了一个附加分量,导致测量管上的2个拾振点产生附加的振动相位差,并且对于一个特定的传感器,该附加分量的量值基本固定,而科氏力对测量管振动的作用随被测流量的增加而增强,故随着被测流量的增加,耦合振动的影响相对减小,引起的流量测量误差随之减小.

Internal coupling vibration of Coriolis mass flowmeter

Resonant Coriolis mass flowmeter(CMF) measures liquid mass flux via the Coriolis theory of the measurement tubes resonant vibration.Actually the external coupling and the internal coupling vibration are widely existent,the operating stability and the measurement precision are directly influenced.The external coupling vibration was resolved by increasing the straight pipelines or strengthening the sensor fixure,but the internal coupling vibration is absence of flawless theoretical guidance and solution.The internal coupling vibration phenomenon and the influence to measurement precision of the sensor were put forward on the basis of the Coriolis mass flowmeter operating mechanism,the comparison experiments of the CMFs with internal coupling vibration and without internal coupling vibration were made by using Polytec laser doppler vibrometer,it was revealed that the internal coupling vibration is tantamount to the additive weight on the main vibration,the additive phase difference was induced.For the special CMF,the additive weight is mostly steady,but the Coriolis force increases with the fluid flux,therefore the influence of internal vibration decreases with the increased fluid flux and the measurement error is decreased.