弯头对大口径热量表电磁流量传感器测量特性的影响

发布时间：2018-07-23 07:59

【摘要】：在流体输配管网系统中大量使用热量表进行能源计量,是实现“节能减排”这一基本国策的重要基础,而热量表计量数据的有效性直接决定了能耗数据的统计结果是否可靠。流量传感器的测量误差对于热量表的总体测量误差影响较大,因此本文选取实际工程中常用的大口径热量表中的电磁流量传感器为研究对象,采用实流实验与数值模拟相结合的方法研究了不同弯头组合形式安装条件对电磁流量传感器测量特性的影响。通过对电磁流量传感器的工作原理、主要优缺点和测量误差产生的原因等进行分析可知,由不同安装条件造成的传感器测量段内部流场的非轴对称分布对测量误差的影响尤为明显。为此进行了大口径电磁流量传感器热态运行条件下的基线实验和相关弯头组合实验,即以某台DN150口径的电磁流量传感器在基线管段的实验数据得到其在实际运行状态下的测量误差,以此作为基准与不同弯头安装条件下的实验数据进行对比,得到安装条件所附加的误差分量,从而分析此表具在实际安装条件下的测量特性。在对单弯头内部流场理论速度分布进行分析的基础上,利用fluent软件研究单弯头内部迪恩涡流的速度重组情况,给出弯头不同截面处的流线、速度云图、压力云图、峰值速度、纵向和横向速度分布的变化情况,并形象地模拟出由于离心力和粘性力综合作用管道内二次流的产生、发展和衰减过程。对平面S型双弯头、异面双弯头、平面弯头组合、弯头蝶阀全开组合等上游安装条件进行了模拟,给出了不同截面处的速度分布、压力分布以及流场结构,形象地表现出这几种局部阻力部件对下游测量段流场产生扰动的过程。在本模拟管路情况下,平面S形双弯头和异面双弯头对下游流场扰动最强,其他弯头等组合次之,其对电磁流量传感器测量特性的影响与对应的实验结果测量偏差相近。
[Abstract]:It is an important foundation to realize the basic national policy of "energy saving and emission reduction" by using a large number of heat meters for energy metering in fluid transmission and distribution network system. The validity of heat meter metering data directly determines whether the statistical results of energy consumption data are reliable or not. The measurement error of the flow sensor has a great influence on the overall measurement error of the heat meter. Therefore, the electromagnetic flow sensor in the large caliber heat meter, which is commonly used in the practical engineering, is chosen as the research object in this paper. The effect of installation conditions of different elbow combinations on the measurement characteristics of electromagnetic flux sensor was studied by combining real flow experiment with numerical simulation. Through the analysis of the working principle, the main advantages and disadvantages of the electromagnetic flux sensor and the causes of the measurement error, we can know that, The non-axisymmetric distribution of the flow field in the sensor section caused by different installation conditions has an obvious effect on the measurement error. For this reason, the baseline experiment and the related elbow combination experiment are carried out under the condition of hot operation of the large aperture electromagnetic flow sensor. Based on the experimental data of a DN150 electromagnetic flux sensor in the baseline pipe section, the measurement errors in the actual operating state are obtained, which are compared with the experimental data under different elbow installation conditions. The error components attached to the installation condition are obtained, and the measurement characteristics of the instrument under the actual installation conditions are analyzed. Based on the analysis of theoretical velocity distribution of flow field in single bend, the velocity recombination of Dean eddy current in single bend is studied by using fluent software, and the streamline, velocity cloud diagram, pressure cloud diagram and peak velocity of different sections of bend are given. The variation of longitudinal and transverse velocity distribution and the process of secondary flow generation, development and attenuation in the pipeline due to the combined action of centrifugal force and viscous force are vividly simulated. The upstream installation conditions such as plane S-type double elbow, cross-plane double bend, plane bend combination, and full opening combination of bend butterfly valve are simulated, and the velocity distribution, pressure distribution and flow field structure at different cross-sections are given. The process of disturbance of these local resistance components to the flow field in the downstream measurement section is vividly demonstrated. In the case of the simulated pipeline, the plane S-shaped double elbows and the cross-plane double elbows have the strongest disturbance to the downstream flow field, and the other elbows are the second. The effect on the measurement characteristics of the electromagnetic flux sensor is similar to the corresponding experimental results.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP212

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