探头式电磁流量计的理论研究和样机试验

本文分析了探头式电磁流量计的基本原理。根据电磁学和流体力学的理论求得了圆柱二电极、圆柱四电极、椭圆柱以及流线型柱体探头感应电动势的解析解。文中还讨论了边界层绕流圆柱探头和有限区间对探头输出信号的影响。从理论解可以看出,探头电极间的感应电动势与来流速度之间呈明显的线性关系。此外,文中还推荐了几种延迟或避免探头表面发生边界层分离的方法。对于圆柱和椭圆柱样机的实验证实了理论分析的结果。

THEORETICAL STUDY AND MODEL EXPERIMENTS OF PROBE-TYPE ELECTROMAGNETIC FLOWMETER

The present paper pinpoints the basic principle of probe-type electromagnetic flowmeters. On the basis of both electromagnetics and fluid mechanics, analytical solutions to the flow induced potential for different types of the meter, including circular cylinder probes with one or two pairs of electrodes, elliptical cylinder probe and streamlined cylinder probe, have been obtained. The effects of boundary layers of the flow past a circular cylinder probe and the limited flow field on the probe output are also dealt with. The theoretical solutions show a clear linear relationship between the flow induced potential produced on the probe electrodes and the approach velocity. Some methods to postpone or avoid the boundary layer separation happening on the surface of the probe are suggested. The experiments on circular and elliptical cylinder model probes substantiate the theoretical results.