用PIV技术测量幂律流体同心环空螺旋流的流场

为研究幂律流体同心环空螺旋流的流动特性,建立了流体的同心环空螺旋流动实验模型。利用PIV(粒子图像测速仪)系统拍摄各种情况下环空螺旋流场中粒子的图像,对数据进行分析处理。结果表明:幂律流体在同心环空管道内做螺旋流动时,流量、流体黏滞性的增大或内管旋转角速度的减小都可以使压力梯度增大;其它条件相同时,压力梯度或流量的增大可以使轴向速度增大,促进紊流发生;压力梯度一定时,黏滞性的减小或内管旋转角速度的增大可以使轴向速度增大,促进紊流发生。将所有工况下实测速度与理论计算速度进行对比,最大相对误差为4.8%,理论与PIV测试实验结果吻合得较好。

To measure the flow field of power law fluid's helical flow in concentric annulus with PIV technology

In order to research into the flow characteristic of power law fluid's helical flow in concentric annulus,an experimental model was established.Particle images in various flow fields of annulus helical flow were screened with PIV(Particle Image Velocimetry) technology.The results indicate that when power law fluid is doing helical flow in concentric annulus pipeline,increase of flow rate and fluid's viscosity and decrease of inner pipe's revolution can make the pressure gradient increase;when other conditions are the same,the increase of pressure gradient or flow rate can make the axial velocity increase and promote the happening of turbulent flow;when the pressure gradient is constant,decrease of viscosity or increase of inner pipe's revolution can increase the axial velocity,and promote the happening of turbulent flow.Actually measured velocity and theoretical arithmetic velocity in all conditions were compared,the biggest relative error is 4.8%,and the theory tallies with PIV testing experiment results very well.