电磁流量计测量直管内速度及管长的CFD 研究

电磁流量计是一种广泛采用的流量测量仪表,测量直管长度对于保证测量管内流速轴对称分布及电磁流量计计量精度起着关键性作用.本文采用CFD数值手段对电磁流量计测量直管长度及管内流速轴对称分布特性展开研究.为了准确地研究流速分布的轴对称特性,提出了定量衡量流速分布轴对称程度的速度对称偏差度,并基于此研究了不同内径、不同过流量条件下测量管内的流速分布轴对称特性和电磁流量计对测量直管长度的要求,为电磁流量计的检定、安装、应用提供科学理论依据,为依托项目建立高精度流量计量标准装置奠定基础.

Study on velocity distribution and length of measured straight pipes for electromagnetic glowmeter based on CFD method

The electromagnetic flowmeter is a widely used flow measurement instrument, and the length of measured straight pipe plays a key role in ensuring both the axisymmetrical velocity distribution of the flow in the pipe and the measurement accuracy of electromagnetic flowmeter. In this paper, the length of mea- sured straight pipe and the axisymmetrical properties of velocity distribution in the pipe are studied based on CFD numerical method. In order to study the axisymmetrical degree of velocity distribution in the mea- surement pipe accurately and quantitatively, a new method, symmetric deviation degree, is presented. With this method, the axisymmetrical properties of velocity distribution of the flow in the pipes with different di- ameters and flowrates are studied, and also the required lengths of the electromagnetic flowmeter on the measured straight pipes are calculated. The conclusions provide scientific theory for the verification, installa- tion and application of electromagnetic flowmeter as well as foundation for the supporting project to estab- lish high-precision flow measurement standard equipment.