基于射流原理的气体流量计研制

发布时间：2018-05-03 05:05

本文选题：射流流量计 + 斯特劳哈数　；参考：《中国计量大学》2016年硕士论文

【摘要】：射流流量计是一种利用附壁效应附加反馈通道产生流体振动的流量计,在较宽的流量范围内,其振荡频率与流量呈线性关系。射流流量计具有体积小,使用寿命长,理论测量下限低,测量精度高等特点,在家用燃气、水和医学流体等小流量测量场所具有广泛的应用前景。目前对射流流量计的研究主要集中于平面式射流振荡器。但是,对于平面式射流振荡器而言,其流体振荡平面与管道轴线在同一平面内,致使上游管道内流量压力脉动容易对射流振荡器内部流场产生干扰,降低了射流流量计的测量精度。此外,传统射流流量计还存在抄表不便,不易标定等问题,限制了其应用范围。为此解决上述问题,本文在前人研究的基础上,研制了一种新型射流流量计,主要完成工作如下:(1)射流振荡器建模与仿真研究。根据射流的附壁效应,设计了由三层射流“双稳”元件为核心构成的射流振荡器,使其流体振荡平面与管道轴线不在同一平面内,提高射流振荡器的抗干扰能力。在Solid Works软件中,建立新型射流振荡器的机械模型。将机械模型导入Gambit软件,抽出流体域,划分网格。将网格模型导入FLUENT软件,模拟射流在射流振荡器内部的流场状态。在射流振荡器的关键位置布置监测点,在相同流量下,监测各关键位置的压力变化,确定压力传感器的监测位置。同时,在不同流量下,观测射流振荡频率,获得振荡频率与流量的对应关系。(2)系统硬件与软件设计。射流传感器输出信号微弱,易受到外界干扰影响,测量精度降低。为提高流量计的测量精度,设计了微弱信号处理电路。根据射流流量计的应用需求,设计了按键电路、LCD液晶显示电路、存储电路、脉冲输出电路和GSM无线通讯电路。根据模块化的设计原则,将系统软件分为频率采集、流量计算、脉冲输出、数据存储、GSM无线通讯和按键子程序。(3)实验研究。通过相关实验平台的搭建,对射流流量计样机进行实验研究,由实验数据得到流量计误差和重复性,并分析其不确定度来源。实验结果表明,该射流流量计测量精度高,量程宽。
[Abstract]:Jet Flowmeter is a kind of Flowmeter which uses the additional feedback channel of wall attachment effect to produce fluid vibration. In a wide flow range, the oscillation frequency is linearly related to the flow rate. Jet Flowmeter has the characteristics of small volume, long service life, low theoretical measurement limit and high measurement precision. It has a wide application prospect in small flow measurement sites such as domestic gas, water and medical fluid. At present, the research of jet Flowmeter is mainly focused on plane jet oscillator. However, for a plane jet oscillator, the fluid oscillation plane is in the same plane as the pipeline axis, which makes the flow and pressure pulsation in the upstream pipeline easily interfere with the flow field inside the jet oscillator. The measurement accuracy of jet Flowmeter is reduced. In addition, the traditional jet Flowmeter has some problems, such as inconvenient meter reading and difficult calibration, which limits its application scope. In order to solve the above problems, a new jet Flowmeter is developed based on the previous studies. The main work is as follows: 1) Modeling and simulation of jet oscillator. According to the wall-attached effect of the jet, a jet oscillator composed of a three-layer jet "bistable" element is designed. The fluid oscillation plane is not in the same plane as the pipeline axis, and the anti-jamming ability of the jet oscillator is improved. The mechanical model of a new jet oscillator is established in Solid Works software. The mechanical model is imported into Gambit software, and the fluid domain is extracted and meshed. The grid model is imported into FLUENT software to simulate the flow field of jet in the jet oscillator. The monitoring points are arranged at the key position of the jet oscillator, and the pressure change at each key position is monitored under the same flow rate, and the monitoring position of the pressure sensor is determined. At the same time, the corresponding relationship between the oscillation frequency and the flow rate is obtained by observing the frequency of the jet oscillation under different flow rates. The hardware and software design of the system is obtained. The output signal of jet sensor is weak, easy to be affected by external interference, and the measurement accuracy is reduced. In order to improve the measuring accuracy of Flowmeter, a weak signal processing circuit is designed. According to the application requirements of jet Flowmeter, the key circuit, LCD LCD display circuit, storage circuit, pulse output circuit and GSM wireless communication circuit are designed. According to the modular design principle, the system software is divided into frequency acquisition, flow calculation, pulse output, data storage GSM wireless communication and keystroke subprogram. Through the construction of the related experimental platform, the experimental research on the prototype of the jet Flowmeter is carried out, the error and repeatability of the Flowmeter are obtained from the experimental data, and the source of uncertainty is analyzed. The experimental results show that the jet Flowmeter has high measuring accuracy and wide measuring range.
【学位授予单位】：中国计量大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TH814

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