流速分布未知二维流场流量测量方法研究

发布时间：2019-05-12 15:53

【摘要】：工业生产中涉及许多大管径管道流量测量问题,由于安装条件的限制,管道内的流体不能充分发展,因此管道内的流体流速分布未知。为了准确测量大管径管道内速度分布未知流场的流量,本文采用插入式电磁流量计,通过测取管道内多点流速来推算管内流量。本文对圆形管道内二维流场流速分布和特征点数学模型、插入式流量计原理以及测量探头的结构进行了理论研究,并且设计了多探头插入式电磁流量检测装置和实验方案。此外,本文还提出一种适用于流速分布未知非充分发展管流的多测点流速流量计算方法—拟合曲线法。最后,本文应用FLUENT软件进行仿真实验:1.构建出多个非充分发展流场进行流场分析,选出最优特征点数学模型—“对数-切比雪夫”法;2.对插入式流量计附近流场进行数值模拟,分析插入式流量计对流场影响并对比两种结构插入式测量探头的优劣;3.对插入多探头插入式电磁流量装置的管道进行数值模拟,并得到各测点的仿真数据。利用MATLAB软件对仿真实验得到的多点流速分别基于拟合曲线法和算数平均法进行融合计算,对两种计算方法进行对比分析。通过对仿真数据的处理和分析,最终证明了拟合曲线法比起传统的算数平均法,大大提高了测量精度,尤其适用于流速分布未知的非充分发展管道的多测点流量计算。
[Abstract]:Many problems of flow measurement of large diameter pipeline are involved in industrial production. Due to the limitation of installation conditions, the fluid in the pipeline can not be fully developed, so the distribution of fluid velocity in the pipeline is unknown. In order to accurately measure the flow rate of unknown flow field in large diameter pipeline, this paper uses plug-in electromagnetic Flowmeter to calculate the flow rate in the pipe by measuring the multi-point velocity in the pipeline. In this paper, the mathematical model of velocity distribution and characteristic point of two-dimensional flow field in circular pipeline, the principle of plug-in Flowmeter and the structure of measuring probe are studied theoretically, and the multi-probe plug-in electromagnetic flow detection device and experimental scheme are designed. In addition, this paper also presents a multi-point velocity flow calculation method, the fitting curve method, which is suitable for the unknown velocity distribution and not fully developed pipe flow. Finally, the simulation experiment is carried out by using FLUENT software: 1. Several underdeveloped flow fields are constructed to analyze the flow field, and the optimal characteristic point mathematical model-logarithm-Chebyshev method is selected. 2. The numerical simulation of the flow field near the plug-in Flowmeter is carried out, and the influence of the plug-in Flowmeter on the flow field is analyzed and the advantages and disadvantages of the two kinds of plug-in probe are compared. The pipeline inserted into the multi-probe plug-in electromagnetic flow device is simulated, and the simulation data of each measuring point are obtained. The multi-point velocity obtained from the simulation experiment was calculated by MATLAB software based on the fitting curve method and the arithmetic average method respectively, and the two calculation methods were compared and analyzed. Through the processing and analysis of the simulation data, it is proved that the fitting curve method greatly improves the measurement accuracy compared with the traditional arithmetic average method, especially suitable for the multi-measuring point flow calculation of the underdeveloped pipeline with unknown velocity distribution.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB937

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