超声波换能器安装方式对渠道水流特性的影响

Influence of Ultrasonic Transducer Installation Method on Flow Characteristics of Channel

换能器安装形式的不同会导致同一声道上流速分布不均匀,从而影响超声波流量计的测流精度。为解决这一问题,基于流速—面积法,通过实测与模拟相结合的方法,在矩形渠道上设置换能器V型和Z型2种安装形式,分析换能器安装角度为30°~60°(梯度为5°)超声波流量计的测流精度。试验结果表明,换能器安装形式为V型,安装角度为40°~45°时,流量相对误差值为-0.06,安装形式为Z型,安装角度为40°~45°时,流量相对误差值为-0.09,换能器V型安装形式的测流精度较高。对矩形渠道建立三维模型,通过CFD模拟不同工况下渠道水流流态与速度分布情况,模拟结果表明,换能器安装角度为60°时,产生直径为5.6cm漩涡,安装角度为30°时,进水口到流速均匀分布的距离为0.5 m,安装角度为45°时,进水口到流速均匀分布的距离为0.3 m,产生直径为3 cm漩涡。换能器安装角度为45°时测流段的流速对称且分布均匀,对涡流和流速分布影响较小。

The different arrangements of transducers will lead to uneven distribution of flow velocity on the same channel,which will affect the flow measurement accuracy of the ultrasonic flowmeter.To solve this problem,based on the velocity-area method,this paper sets two installation forms of transducer V-type and Z-type on the rectangular channel through the combination of measurement and simulation and analyzes the flow measurement accuracy of the transducer installation angle of 30°~60°(gradient of 5°)ultrasonic flowmeter.The experimental results show that the relative error value of the flow rate is-0.06 when the installation angle of the transducer V-type arrangement is 40°~45°,and the relative error value of the flow rate is-0.09 when the installation angle of the Z-type arrangement is 40°~45°.The error value is reduced by 0.03,and the transducer V-type arrangement has higher flow measurement accuracy.The three-dimensional model of the rectangular channel is established,and the flow pattern and velocity distribution of the channel under different working conditions are simulated by CFD.The simulation results show that when the installation angle of the transducer is 60°,a vortex with a diameter of 5.6 cm is generated.When the installation angle is 30°,the distance from the inlet to the uniform distribution of the flow velocity is 0.5 m.When the installation angle is 45°,the distance from the inlet to the uniform distribution of the flow velocity is 0.3m,and a vortex with a diameter of 3 cm is generated.When the installation angle of the transducer is 45°,the flow velocity in the flow measurement section is symmetrical and evenly distributed,which has little effect on the eddy current and flow velocity distribution.