涡街流量计测量气液混相流的不确定度  

Measuring the Uncertainty of Gas-liquid Mixed Flows Using Vortex Flowmeter

作　　者：孙志强[1] 郭洁[1] 张宏建[2] 周孑民[1] 

机构地区：[1]中南大学能源科学与工程学院,长沙410083 [2]浙江大学控制科学与工程学系工业控制技术国家重点实验室,杭州310027

出　　处：《化工自动化及仪表》2008年第3期46-50,共5页Control and Instruments in Chemical Industry

基　　金：中南大学博士后科学基金资助项目

摘　　要：涡街流量计可用于部分混相流的测量，但迄今为止有关混相流对涡街流量计测量特性的影响还缺少理论研究和实践经验。在体积含气率为2．0％-15．0％的范围内，评定了用涡街流量计测量气液混相流的不确定度，提出涡街流量计测量气液混相流的不确定度计算式。实验以空气和水为介质产生气液混相流，涡街信号通过管壁差压法采集，涡街频率通过功率谱分析获得。结果表明在保持涡街流量计一定测量准确度的前提下，涡街流量计相对扩展不确定度随气液混相流流量及其体积含气率的分布比较均匀；在涡街频率测量的不确定度分量中，由重复性和复现性引起的相对标准不确定度随流量的变化呈现出较强的随机性，而由频率分辨率引起的相对标准不确定度则随着流量的增加而减小。在本研究的流量与体积含气率范围内，由气液混相流引起的涡街流量计附加相对不确定度小于2．0％。这一研究为分析气液混相流对涡街流量计测量特性的影响提供了有益的借鉴。Vortex flowmeter can be used to measure some mixed flow, however, so iar theoretical researches and practical experiences about the influence of mixed flows on the performance of vortex flowmeter were seldom reported. In this paper uncertainties of gas-liquid mixed flows using vortex flowmeter were evaluated when the volume void fraction the vortex frequencies were obtained from power spectral analyse. The results show that the relative expanded uncer- tainties distribute quite uniformly with the gas-liquid mixed flow rates and volume void fractions under a certain accu- racy of the vortex flowmeter. Second, among the uncertainty components of vortex frequency measurement, the relative standard uncertainties caused by the repeatability and reproducibility vary randomly with the flow rates, whereas the relative standard uncertainty caused by the frequency resolution decreases with the increase of flow rates. Third ,in the flow rates and volume void fractions studied, the additional relative uncertainty introduced by the gas-liquid mixed flows is less than 2.0% which are useful for analyzing the effect of gas-liquid mixed flows on the characteristics of vortex flowmeter.

关 键 词：不确定度估计 涡街流量计 气液混相流 测量模型 传播律 

分 类 号：TQ056[化学工程]