提高弯头下游均速管流量传感器测量精度的研究

当均速管流量传感器安装在弯头下游时,由于流体流动为非充分发展湍流,会增大其流量测量的误差.为提高流量测量精度,提出了在90°弯头下游安装流动调整器改善速度分布对称性,减小测量误差的方法.采用计算流体力学(CFD)仿真分析与实流实验相结合的方法,基于NEL流动调整器,设计出了改进型的流动调整器结构.经仿真和实验验证,安装改进的流动调整器后,均速管流量传感器的线性度误差减小到了0.176%.流动机理分析发现,上游流体速度剖面对称性是影响传感器误差的关键因素.数据表明,CFD仿真预测线性度误差的偏差小于0.056%.

Improving Accuracy of Averaging Pitot Tube Flow Sensor at Downstream of Elbow

When the averaging Pitot tube flow sensor is installed at the downstream of elbow,the flow regime is not fully-developed turbulence,which will increase the error of flow measurement. In order to improve the accuracy of flow meas-urement,a method to reduce the error by installing a flow conditioner at the downstream of the 90＆#176;elbow for reforming the symmetry of flow velocity profile was put forward. Based on the NEL flow conditioner,the improved flow conditioner was designed by the method of computational fluid dynamics（CFD）simulation and analysis combined with real flow experiment. Verified by the simulation and experiment,after installing the improved flow conditioner,the linearity error of the averag-ing Pitot tube flow sensor was decreased to 0.176%. It has been found through analyzing the flow mechanism that the sym-metry of the velocity profile at the upstream of the flow sensor is the main factor affecting the error of the sensor. It is indi-cated in the data that the difference of the linearity error predicted by the CFD simulation is less than 0.056%.