【作者】 朴立华；

【导师】 张涛；

【作者基本信息】 天津大学 ， 检测技术与自动化装置， 2011， 博士

【摘要】 浮子流量传感器结构简单、成本低廉、使用方便、工作特性稳定、应用面广,特别是金属管浮子流量传感器,工作可靠,是过程控制领域重要的流量仪表之一。寻求有效手段优化浮子流量传感器的结构以改善其性能,以及探求浮子流量传感器的粘度影响规律等问题一直是众多专家学者所关注的重点问题,本论文从这两个方面对浮子流量传感器进行了研究。对设计与优化大口径锥管浮子流量传感器的结构和几何参数的方法进行了研究,以DN100和DN200短管型金属浮子流量传感器为例,详细介绍了对其进行优化设计的研究工作;利用CFD方法对不同结构的孔板浮子流量传感器进行比较和分析,设计了线性度好、压力损失小的双锥形孔板浮子流量传感器;提出根据线性度转折点处流量与量程上限的比例关系确定双锥形浮子锥台高度和锥台连接处直径的方法;以DN100孔板浮子流量传感器为例,给出了双锥形结构的最优参数。依据粘性流体力学的边界层理论及流动阻力理论,考虑粘性摩擦力对浮子的作用,从理论上分析了影响孔板浮子流量传感器体积流量的因素;采用理论分析与CFD数值计算相结合的方法,研究了流体温度变化对金属管浮子流量传感器测量性能的影响;在可变温油装置上对孔板浮子流量传感器进行实验研究,给出了粘度影响公式的一般形式及DN25孔板浮子流量传感器的解析公式;利用CFD方法从微观流场的角度研究了孔板浮子流量传感器的粘度影响机理,提出了利用CFD方法对其进行研究时的临界雷诺数及不同雷诺数下的粘度模型。采用模块化思想设计了浮子流量传感器通用仿真平台。该平台自带建模和计算所用的全部jou文件以及浮子流量传感器结构参数数据库,能够根据流体属性自动计算前直管段Re数并正确选择粘度模型,可读性强,操作简单。浮子流量传感器结构优化和粘度影响研究中所应用的方法,可拓展到其他类型流量传感器的设计和研究中。更多还原

【Abstract】 Ratometer has such features as simple structure, low cost, convenient operation, stable operating characteristics and wildly application. Especially the metal tube rotameter is one of the most important flow meters in process control field. Many experts and scholars have been concerned on looking for an efficient way to optimize the transducer structure of rotameter in order to improve its performance and searching for the viscosity influence law of rotameter, etc. From the above two issues, this paper had been studied rotameter as well.This paper studied on designing and optimizing the transducer structure and geometric parameters of large diameter cone rotameter. Taking 200mm diameter and 100mm diameter short-tube rotameter as examples, the design thought was introduced in detail. The CFD method was used to compare and analyze the different structure of orifice rotameter. And a kind of dual-cone orifice rotameter designing with high linearity and low pressure loss was given. This paper proposed the method of determining the cone height of dual-cone float and the diameter of cone connection part, which was based on the ration between the linear turning point flow and maximum flow. The dual-cone structure optimal parameters of DN100 orifice rotameter were presented.Based on viscous fluid theory of the boundary layer and flow resistance, concerned the viscous friction force effect of the float, the impact factors of orifice rotamater volume flow were analyzed theoretically. The effect of the measured flow temperature on the metal tube rotameter performance was studied by combining theoretical analysis and CFD numerical calculation. The experiments of orifice rotameter on variable temperature oil calibration apparatus were done, the general viscosity formula and the analytical formula of DN25 orifice rotameter were given. CFD method was used to study the viscosity influence of orifice rotameter in micro-flow field perspective, the critical Reynolds number and viscosity model under different Reynolds numbers was proposed for CFD method.Based on the modularization idea, this paper designed a common database which has the entire jou file for modeling and calculation, and structure parameters of rotameter transducer. A highly readable and simple-operating rotameter common simulation platform was designed as well which can calculate the Reynolds number of upstream straight section automatically based on fluid properties and choose the proper viscosity model.These methods applied in optimizing the rotameter transducer structure and studying viscosity effect presented in this paper can be extended to the design and application of other type flow meter.更多还原