【摘要】 前向插入式流速仪在工作时其探头会对待测流场造成干扰,该文对简化流速仪模型的干扰范围进行了测量和分析。简化模型仿毕托管(Pitot tube)形状,水平放置于明槽流场中,采用粒子图像测速(PIV)技术测得代表性平面瞬时二维流场。通过分析流场的沿程变化特征,确定了流速仪模型对其正前方水流的影响距离。实验结果表明:流向速度随距模型顶点距离的增大逐渐增加最后趋于来流速度,而水流的展向速度、紊动强度和雷诺应力(Reynolds stress)均随距模型顶点距离的增大而逐渐减小最后趋于稳定;流速仪对其前方水流的流速影响距离较大,对紊动强度的影响距离较小;流速仪对前方水流影响距离随模型直径增大而增大,在实验条件下,影响距离与模型直径成正比。更多还原

【Abstract】 Horizontal plug-in flow meters disturb the velocity fields when deployed to measure rates flow.The spatial extent of such disturbances has been experimentally studied here on a simplified flow meter model.The Pitot tube used as the flow model was placed horizontally in the water flow with instantaneous two-dimensional velocity fields also measured by particle image velocimetry(PIV).Analysis of the spatial variations of the velocity fields in front of the model shows that the streamwise velocity increases with the distance from the model nose and gradually approaches that of the incoming flow with the spanwise velocity,turbulent intensities,and Reynolds stresses decreasing with the distance. The streamwise velocity requires the longest distance to recover from the disturbance with the turbulent intensity requires the shortest distance.The spatial extent of the disturbance is proportional to the flow meter diameter.更多还原