Three Components- and Tomographic-PIV Measurements of a Cyclone Cooling Flow in a Swirl Tube
Three Components- and Tomographic-PIV Measurements of a Cyclone Cooling Flow in a Swirl Tube
复制标题
旋流管中旋风分离器冷却流的三分量和层析 PIV 测量
DOI：
10.1115/gt2013-94424
复制
发表时间：
2013
影响因子：
2.6
通讯作者：
A. Cabitza
中科院分区：
文献类型：
--
作者：
Christoph Biegger;B. Weigand;A. Cabitza
旋流冷却是涡轮机叶片冷却的一种非常有效的方法。然而，这种系统中的流动是相当复杂的。为了了解前缘旋流冷却室内的流动结构，采用粒子图像测速技术（PIV）对两个切向进气道的前缘旋流冷却室内的速度场进行了实验研究。所研究的涡流管长1 m，直径为50 mm。它代表了前缘涡流室的放大通用模型。由体积速度和旋流管直径定义的雷诺数范围为10，000至40，000，旋流数为5.3。分别使用两台和四台CCD摄像机，用体视PIV和层析PIV测量了管轴中心平面内的速度场。Tomographic-PIV是一种三维PIV技术，它依赖于与立体PIV中的平面相对的测量体积中的示踪粒子分布的照明、记录、重建和互相关。为了进行统计分析，计算了2，000个矢量图，评估表明，1，000个集合的样本量就足够了。实验表明，流场的特征是绕管轴的涡系。在管壁附近，我们观察到朝向出口的轴向流，其周向速度分量处于相同的数量级。相反，涡核由轴向回流（涡破裂）组成。对流场的了解有助于预测旋流室中的强化传热区域。Copyright © 2013 by ASME
Swirl cooling is a very efficient method for turbine blade cooling. However, the flow in such a system is quite complicated. In order to gain understanding of the flow structure, the velocity field in a leading edge swirl cooling chamber with two tangential inlet ducts is experimentally studied via Particle Image Velocimetry (PIV). The examined swirl tube is 1 m long and has a diameter of 50 mm. It represents an upscaled generic model of a leading edge swirl chamber. The Reynolds number, defined by the bulk velocity and the swirl tube diameter, ranges from 10,000 to 40,000, and the swirl number is 5.3. Velocity fields are measured in the center plane of the tube axis with stereo- and tomographic-PIV using two and four CCD cameras respectively. Tomographic-PIV is a three-dimensional PIV technique relying on the illumination, recording, reconstruction and cross correlation of a tracer particle distribution in a measurement volume opposed to a plane in stereo-PIV. For statistical analysis 2,000 vector maps are calculated and evaluations show a sample size of 1,000 ensembles is sufficient. Our experiment showed, that the flow field is characterized by a vortex system around the tube axis. Near the tube wall we observed an axial flow towards the outlet with a circumferential velocity component in the same order of magnitude. In contrast the vortex core consists of an axial backflow (vortex breakdown). The gained understanding of the flow field allows to predict regions of enhanced heat transfer in swirl chambers.Copyright © 2013 by ASME