Steady expiratory flow in a model symmetric bifurcation.
Steady expiratory flow in a model symmetric bifurcation.
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模型对称分叉中的稳定呼气流量。
DOI：
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发表时间：
1994
期刊：
影响因子：
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通讯作者：
B. Lieber
中科院分区：
文献类型：
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作者：
Yao Zhao;B. Lieber
采用对称分叉模型模拟人体中央气道上部的稳态呼气流量。一个双色，双组分激光多普勒风速计被用来测量轴向流和二次流在三个不同的雷诺数为518，1036，和2089，对应的迪恩数为98，196，和395。试验段是具有恒定横截面积的对称分叉，分支角为70度。进入两个子分支的流速大致相同。结果表明，在连接面内，子分支中的速度分布偏向内壁。在母管中，就在分流器的下游，速度剖面是双凹的，在中心处有一个倾角，但这很快转变为速度峰值。在横截分叉平面的平面内，抛物线速度分布通过子分支保持不变。在母管中，横向剖面在分流器下游变得平坦，并在分叉母管部分末端下游中心处形成缺陷。速度亏损被限制在中心线附近的一个小区域。在子分支中观察到以对称涡旋为代表的螺旋运动。在母管中，观察到一组由流动的转向引起的四个涡流。
A model symmetric bifurcation was employed to simulate steady expiratory flow in the upper part of the human central airways. A two color, two component laser Doppler anemometer was used to measure both the axial flow and the secondary flow at three different Reynolds numbers of 518, 1036, and 2089, corresponding to Dean numbers of 98, 196, and 395. The test section is a symmetric bifurcation of constant cross-sectional area with a branching angle of 70 degrees. The flow rate into the two daughter branches was about the same. Results show that in the junction plane, velocity profiles in the daughter branches are skewed towards the inner walls. In the parent tube, just downstream of the flow divider, the velocity profile is biconcave with a dip at the center but this is rapidly transformed into a velocity peak. In a plane transverse to the bifurcation plane, parabolic velocity distribution was conserved through the daughter branches. In the parent tube, the transverse profiles became flat downstream of the flow divider and developed a defect at the center further downstream towards the end of the parent tube part of the bifurcation. The velocity defect was confined to a small region in the vicinity of the centerline. Helical motion typified by symmetric vortices was observed in the daughter branches. In the parent tube, a set of four vortices induced by the turning of the flow was observed.