均速管流量计尺寸优化的仿真研究

Geometrical dimensions optimization of averaging pitot tube

均速管流量计检测杆的截面形状,对均速管流量计的性能具有显著的影响,但是具体的影响规律尚不明确.针对该问题,本文利用Gambit软件以及FLUENT软件,研究均速管流量计检测杆截面尺寸与均速管流量计性能之间的关系.通过二维仿真实验,得到了检测杆截面前端半圆半径对其性能的影响规律及湍流模型对输出压差的影响.进而得到适用于空调管道低风速测量的,均速管流量计检测杆截面的最佳结构尺寸.研究结果表明,层流、标准k-模型以及SST k-ω模型相比较,标准k-模型更适合用于空调系统低风速应用背景;减小检测秆截面前端半圆半径,流量系数趋于稳定,但流量系数值变大;增大检测杆截面前端半圆半径,流量系数值变小,然而在3~12m/s低流速范围内,流量系数出现不稳定现象,不过随着检测杆截面前端半圆半径的继续增大,不稳定现象得到了缓解.该研究对设计适用于空调管道低风速测量的均速管流量计,具有一定的参考意义.

The cross section geometrical dimensions of the Averaging Pitot tube have significant unknown influences on its performance,especially in low speed air measurement.The paper studies the effects of cross section geometrical dimensions on the performances of the Averaging Pitot tube with Gambit and FLUENT software.Through the two-dimensional simulation,the decting rod tip radius influences on the tube performances,and turbulence model infuences on the differential pressure,are investigated.And then,the optimum structure size of the Averaging Pitot tube is obtained which is suitable to the measurement of the low air speed available for supply air control in air-conditioning duct.Simulation results show that the standard k~model is more appropriate for low speed applications,comparing withlaminar flow and the SST k~ω model.Withthe decrease of detecting rod front radius,flow coefficient becomes largeand tends to be stable.On the other hand,with the increase of the semi-circle radius,the flow coefficient becomes small and tends to be unstable,especially in the velocity ranges of 3m/s~12m/s.However,the unstable situation can be improved when the semi-cirele radius becomes la ger.This study can be helped to the design of the Averaging Pitot tube applied to the measurement and control of the low air speed,such as in central air condition system.