对称柱塞式微小气体流量校准装置的设计与仿真研究

Design and simulation of symmetric plunger tiny gas provers

为研究微尺度气体流量仪表的计量特性,设计了一套基于动态检测原理的对称柱塞式微小气体流量校准装置.简述了装置的结构及工作原理,并以临界流文丘里喷嘴为检测对象,采用计算流体动力学(CFD)方法,对该校准装置动态检定临界流喷嘴的过程进行仿真研究.获得了仿真条件下缸内气体运动状态参数,缸体压力波动引入的标准不确定度优于0.05‰,温度波动引入的不确定度优于0.02%,满足装置设计要求.研究结果表明,该结构原理的活塞装置能较好地维持试验过程中流量和状态参数的稳定,可以实现微小流量的计量.

In order to study the metrological characteristics of microscale gas flow meters,a symmetric plunger tiny gas prover was proposed based on the principle of dynamic detection.The structure and the working principle were introduced.A computational fluid dynamics(CFD)method was employed to simulate the process of the device during the dynamic calibration of the critical nozzle.The gas motion state parameters inside the cylinder were obtained by simulation.The standard uncertainty caused by the pressure fluctuation of the cylinder block was less than 0.05‰ and the uncertainty of the temperature fluctuation was less than 0.02%,which was sufficient to satisfy the design requirements.Simulation results show that this structural principle of the piston unit is capable to maintain the stability of the flowrate and state parameters during the test,which indicates the potential application of calibration for tiny gas flow.