Measurement of fluid flow in closed conduits - flowrate measurement by means of vortex shedding flowmeters inserted in circular cross - section conduits running full 封闭管道中液体流量的测量.在圆形截面导管中插入涡流流量计来测量流率
The analogy circuits in flowmeter are unable to ensure the measuring precision of flowmeters in fields , and make the span ratio of flowmeter lower than theoretical value 用现有的模拟处理方法，不能保证流量计的现场测量精度，流量计的量程比受限。
The flowmeters based on the principle of flow vibration are widely used . however , they are easily subjected to noises caused by pipe vibrations and fluid turbulence 基于流体振荡原理的流量计应用相当广泛，但是，易受管道振动和流体扰动等噪声的影响。
The main products are : general pressure gauges and their fittings , special pressure gauges , refrigeration meters and their fittings , thermometers , controllers , flowmeters etc 主要经营产品有普通压力仪表及配件、特种压力仪表、制冷仪表及配件、温度仪表、压力温度控制器、流量仪表等。
Digital signal processing systems of vortex flowmeters are developed by the modern digital signal processing technique in order to improve the measurement precision and enhance functions of meters 应用现代数字信号处理技术去研制涡街流量计数字信号处理系统，可以提高涡街流量计的测量精度，增强仪表的功能。
But it is very difficult to develop multiphase flowmeters due to the complexity of flow regimes and inconstancy of flow composition at flowing conditions , thus far there are few practicable multiphase flowmeters available 由于多相流在流动过程中流型复杂、成分多变等原因，使得多相流量计的开发极其困难，到目前为止很少有实用性好的多相流量计。
Furthermore , the development of electromagnetic flowmeter with low frequency rectangular wave excitation is finally selected as the emphasis of research through analyzing the advantages and disadvantages of the different kinds of electromagnetic flowmeters 电磁流量计的设计分析了不同种类的电磁流量计的优缺点,最终选择低频矩形波励磁电磁流量计为研究重点。
The design has the characteristics of high accuracy , low cost and wide measuring range , and thus offers a reference for further developing practical multiphase flowmeters of non - radioactivity pollution , low press loss and non - moving components 该方案具有可靠、成本低、测量范围广的优点，为研制无放射性、无可动部件、低压降的实用性多相流量计提供了借鉴。
