差分式小口径科氏流量计测量方法实验分析

Experimental analysis of measurement method for micro coriolis mass flowmeter with differential tubes

针对小流量计量问题,阐述了一种导流管差分式设计的小口径科氏流量计,两根导流管内流体相向流动,科氏流量计测量值为两管流量之差;详细论述流量信号频率估计、相位差估计的相频匹配方法,以及对估计结果的平滑方法;在3种不同基础流量下开展实验研究,分析了流量计的零点稳定性、测量线性度和测量误差。实验结果表明,差分式流量计的零点与基础流量有较大关系,零点不稳定度估计为0.539 g/min,时间差与质量流量的线性度较好,满量程精度在0.5%以内。

To investigate the problem of small flow measurement,a micro Coriolis mass flowmeter is introduced which is designed with diversion pipe crossed.Liquid in two different tubes flows in the opposite direction.The measurement value of Coriolis mass flowmeter is the difference between the two tubes’flow.A phase-frequency matching method for frequency estimation,phase difference estimation is discussed in detail.Smoothing method for the estimation results is also put forward.Experimental research is carried out under three different basic flows.On this basis,the zero stability,linearity and measurement error of the flowmeter are analyzed.The experimental results show that the zero point of the differential flowmeter has a great relationship with the basic flow.The instability of the zero point is estimated to be 0.539 g/min,and the accuracy of the full range is within 0.5%.The mass flow has a remarkable linearity with the time difference.